Robber Baron Cave Preserve

Preserve Manager: Joe Mitchell
Assistant Manager: Mike Harris

Robber Baron Open House 2019

The next Robber Baron Open House is scheduled for Saturday, September 28, 2019 from 9am to 3pm. This special event only occurs once every 18 months, so don’t miss this rare opportunity! The Open House is open to the public. It is

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Tours at the Robber Baron Open House

The Robber Baron Open House is Saturday, November 11, 2017 from 9:00 am to 3:00 pm and we hope you can attend! Even though advance reservations are now full, they are NOT required to take the regular self-guided tour to

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Robber Baron Open House 2017

The next Robber Baron Open House is scheduled for Saturday, November 11, 2017 from 9am to 3pm. This special event only occurs once every 18 months, so don’t miss this rare opportunity! The Open House is open to the public.

Read More »


TCMA’s Robber Baron Cave has been long known to have a long and interesting history, being the second oldest commercial cave in Texas, a speakeasy during prohibition, and is surrounded by many legends and rumors. Much of what is known is based on oral histories, secondhand stories, and scattered records, but a great deal about the history of the cave has remained shrouded in mystery. In recent years, new research into the cave’s history has uncovered a wealth of information, solving some of the long-standing mysteries, confirming certain tales, and showing that the cave was a well-known and popular local destination in the San Antonio area at that time. Information has appeared from a wide range of sources, including newly available archives of historical newspapers, interviews with people who were involved with the cave in its early days, examination of several local, state and national archives that turned up several photographs, and even careful searches for clues within the cave itself. (A few of the more interesting earliest articles are available for download at the bottom of this page.) Many intriguing mysteries remain and some new ones have been found, so the search goes on. Anyone with stories, documents, or old photos of the cave is strongly encouraged to contact the Preserve Manager.

Legends of Los Quebrantahuesos

Located next to the Old Kings Highway, then the main road from San Antonio to Austin, the cave was frequently visited by curious passersby well back into the 1800s, if not earlier. Graffiti has been found in one passage dating to 1836, with others nearby from the 1860s and 1880s. Early records show that it was known as the Cave of the Quebrantahuesos (Spanish for vulture or bone-breaker) and later as North Loop Cave (for a nearby road). The oldest known newspaper article that mentions the cave, in 1898, tells of troops, who were stationed nearby, exploring the cave “to gratify curiosity” and “trying to discover a new route to the Philippines.”

Two of the oldest dated graffiti samples from 1836 (left) and 1864 (right). Photos by Joe Mitchell.

Two of the oldest dated graffiti samples from 1836 (top) and 1864 (bottom). Photos by Joe Mitchell.

By 1910, the cave was well-known as reported in the El Paso Herald. This article from September provides the earliest descriptions of some of the legends then surrounding the cave:

It is the belief that this passageway leads to a point where is hidden an immense treasure representing the plunder of a band of brigands. Old Mexicans living near tell the tradition of a powerful band of robbers that inhabited the cave during the viceroyships of Texas. They called themselves “Los Quebrantahuesos”, the translation being the sinister words “The Vultures”. Tradition tells of sudden descents on peaceful travellers, of plunder and rapine, and of dragging prisoners to the cave where the final dispatching took place. [1]

Many believed that the cave contained gold and other riches from these Spanish bandits, exciting wild speculation and tales leading to more frenzied of exploration in the cave. In March 1911, the San Antonio Light breathlessly reported on a mysterious wall discovered in the cave and the plans to blast it open:

What mystery lies back of a huge wall—man-made—in the labyrinthian depths of the Cave of the Quebranthuesos…possibly chests of chests of precious stones, diamonds, gold, pieces of eight are buried there, buried for three centuries from the light of day. Others incline to the belief that the bones of [El Diablo] and his men—hemmed in at last in a final struggles with the imperial troops—lie there bleached, with decayed finery and possessions lying about. [2]

Other than these numerous legends, little is known of what the cave was like before commercialization changed it forever. The same March 1911 article reveals some interesting tidbits describing plans to “develop the guano deposits which are to be found in great quantities within the cave.” No such deposits are currently known within the cave and until 2008 bats were only rarely seen in the cave, though their population has been growing in recent years. The cave was also said to have been highly decorated and was known for a time as Crystal Cave. Though nearly all formations are now gone, removed by the thousands of visitors over the decades, careful examination reveals evidence of their former presence throughout the cave. Several articles describe fine specimens of stalactites within the cave and the San Antonio Scientific Society records the donation of one to their collection in 1919.

The oldest known photo from Robber Baron, found on a hand-colored postcard postmarked April 5, 1921.

The earliest known map of the cave appears in a September 25, 1921 article in the San Antonio Light [3]. Discovery of the article provided a great deal of insight into what the cave was like just before its commercial development. The map shows several passages, which, when carefully compared to the modern map, show the entrance was not through the current opening but through the small opening in the side of the sinkhole, then called “Fat Man’s Misery”. This entrance was re-uncovered during the 2004 restoration of the sinkhole. Intriguing names are given to several passages including “Sugar Bowl Hall”, “Old Camp Ground”, “Undertakers Parlor”, “Vimy Ridge” (originating from a WWI battle site), and “To China”. The article also contains two of the earliest known photos of the cave, one showing the Graffiti Room (then called “Five Point” and without visible graffiti) and a second photo whose location has not been identified.


Being a highly complex maze, the cave was site to many an unprepared explorer finding himself or herself lost within. Digging in nearly any spot in the cave reveals layers of string, laid down by those who feared of their ability to find their way out. One can only imagine if any of these explorers ever became confused about whether they were following their own string or that of someone else! By the early 1920s the cave already had a reputation for treacherousness and the frequency with which people became lost. In one early incident, two boys from a military academy were lost and huddled in an out of the way passage until a search party came out from town and did not find them until late at night after they had “about given up hope of rescue.” In another incident, it is related that two men got lost and then worse, ran out of candles:

They had one match left and feared to use it. After hours of crawling on their hands and knees in the darkness, their hands struck something that sounded like tin. After a consultation, they struck their last match—it was a San Antonio undertakers sign. Their hearts, already heavy, sunk to despair as their match burned out. Then they crawled a little farther along and a faint glimmer shone from above. They ran forward and saw the light streaming from the entrance. [3]

In a widely reported incident in October 1922, four young men were believed lost in the cave, prompting a big response. At the entrance of the cave a sign was found that read “Four of us in the cave. Please do not cut any string. It may mean death.” The person who found it became concerned since the sign was wet and appeared to have been there for some time. They reported their find to authorities, which combined with reports from the missing young men’s families, resulted in the police and fire departments mounting a major rescue effort. A Deputy Captain, two Deputy Sheriffs, two police officers and a half dozen firemen mounted a search party into the cave “to determine the fate of the boys.” After the rescue team had been in the cave some time, the young men suddenly emerged at the surface unaware of the events going on around them:

“O, heck,” says one as he sees fire wagons, police patrol, deputy sheriffs, reporters and a crowd at mouth—”We were just having a good time.” [4]

1920s: Open to the Public

Arthur J. Harp, developer and manager of Robber Baron Cave in the 1920s. Photo provided by Charles Spang, Jr.

In 1910, the cave was purchased by George C. Saur, a prominent local businessman who owned numerous buildings throughout San Antonio. He eventually built himself a large home and gardens on the property in which he raised award-winning roses. He was also interested in promoting and eventually developing the cave. With the increasing interest attracted to the cave by the promotion of its mystery and legends in the media, he realized its commercial potential. Just after 1920, Saur hired Arthur Harp to develop the cave as a tourist attraction.  This preparation included: exploration of the cave, excavation of its modern entrance as a larger alternative to the original “Fat Man’s Misery” entrance, building a wooden staircase into the sinkhole, installation of an iron gate, filling passages of the V-shaped slotted floors with tons of rock and dirt to allow for easy walking, and installation of benches and a lighting system. A collapse in the sinkhole led to Harp building a tunnel structure leading into the entrance and eventually sealing the original entrance.

In 1923, the first of an estimated 300,000 people began to tour the newly opened Robber Baron Cave.  The name was dreamed up by Harp to give it an outlaw mystique. To further its legend, Arthur spread stories of Indian massacres (whose “ghosts haunt the cave”) and of monks who would escape “bloodthirsty Injuns” by entering Robber Baron Cave and exiting at San Pedro Park 8 km away! Although some of his stories may seem farfetched today, they were taken quite seriously at that time.

The Lighted Passage in 1923. Note the glass insulators and light bulb. The passage floor is about 18 inches lower in this photo than it is today. Photo by Harvey Patteson.

After visiting the cave in 1929, W.A. Ownby wrote for the Dallas Morning News that the cave was once a hideout for a band of thieves ruled by a “robber baron” whose “depredations extended over a wide area of the southwest”:

If the walls of this cave could talk they probably would reveal tales of crime which cause the blood and thunder stories of the wild and woolly west to pale into insignificance…The chieftain of the band ruled his men with an iron hand and that when one was sent out on a mission of crime, if he failed, he never returned. [5]

Arthur Harp was himself a storyteller and something of a larger than life character, so he knew what sort of tales appealed to the public, often modeled them after factual recent events. For example, in 1886, the skeleton of Frank Harris was discovered in a cave near Helotes thereafter called “Robber’s Cave”.  The discovery and ensuing murder trial of Frank and T.S. Scott attracted much publicity. In 1910, Charles Merritt Barnes wrote about Robber’s Cave:

It [the cave] takes its name from a gang of outlaws whose leader was known as Jim Pitts. This gang operated extensively for about 100 miles around San Antonio and this cave was their rendezvous. They robbed country post offices, stores, stages, and even churches. The musical instrument, or organ, belonging to a church not very far from this cave was stolen by this gang. [6]

As another example, in March 1909, quarrying immediately north of San Pedro park led to the discovery of a cave apparently used by Native Americans. An article in the San Antonio Light reports:

Laborers…discovered an Indian tomb filled with skeletons of human beings, Indian war relics, articles of peculiar metal formation, spear and arrow points…The theory is advanced that the bones taken therefrom represent the remains of a once giant race that once lived in the northern portion of the country ages ago. [7]

Publicity photo of “robbers” hiding out in Robber Baron Cave. Photos like this were likely used to promote the cave. Note the light bulb on the ceiling. Photo by Harvey Patteson.

Robber Baron’s original crawlway entrance made it an unlikely choice for use by robbers or Indians, yet Harp drew upon these earlier tales as a source of legends and ideas to enhance the cave’s commercial appeal. He even went so far as to hire a Cherokee to paint a large mural on the inside wall of the sinkhole and have “pictographs” painted on the ceiling of one of the rooms. The cave received an early boost by the widely reported story of Floyd Collins entrapment in Sand Cave in Kentucky in 1925, after which many curious people came “to visit the local cave to get a better understanding of the fate of Collins” wondering whether “the Robber Baron’s Cave is like the one in Kentucky where the explorer met his death.”

For 50 cents, Harp would lead eager tourists down wooden stairs in the sinkhole and then into the cave, where about 250 yards of passage were illuminated. First stop was Maggie’s Den, which had a table and benches to sit on. It served several functions—one was as a waiting area for people to tour the cave. Second, it could be rented out for catered parties. Harp would lock people into Maggie’s Den so they wouldn’t wander off into other parts of the cave, and then would release them at a prearranged time. Third, during prohibition years the door into the Maggie’s Den had a peephole and was used a speakeasy. Frank Pena remembers “we use-ta get drunk awful quick in there.” Word of the speak-easy got around because on July 20, 1925, the cave was raided by government Prohibition Agents in search of “a still and modern Monte Carlo” operated by a gang of bootleggers. As reported in the San Antonio Light:

Primed for a big raid, the agents entered the cave and searched for hours. Nothing could be found—not even the way out. For three and one-half hours every turn was investigated, only to end in a blank wall. Flashlights were growing dim from constant use and matches had all been used. Prospects weren’t pleasing. [8]

Fortunately for the agents, a man stationed at the entrance grew concerned and alerted help, who located the agents, leading them out of the cave. They never found what they were seeking. Another visitor to Maggie’s Den, Ted Zettner, remembers having some “home brew” but he had to leave the cave quickly. To hide the evidence he slid his bottle around a corner in the wall. During the survey of the cave in 1976, a peculiar old bottle was found by George Veni. Later, upon hearing Zettner’s story and showing it to him, Zettner confirmed that it was the one he had left behind many decades before.

From Maggie’s Room, tours of the cave continued to the next stop in the Devil’s Kitchen, which was described as having stone benches and artificial floor-to-ceiling columns. When a switch was flipped, the room would be dramatically bathed in colored light, illuminating a coffin and skeleton hidden in a side alcove. Beyond the Devil’s Kitchen was the “Bottomless Pit”, crossed by a narrow board, the bottom of which could not be seen by lantern light, and Gypsum Alley, a narrow passage covered with popcorn formations.

Tourists in the Devil’s Kitchen posing with a fake skeleton. Photographer unknown.

The food concession stand at Robber Baron. Photographer unknown.

Advertisement for the cave was primarily by word of mouth and by pictures painted on Harp’s old Whippet truck. Its location on one of the main roads into San Antonio and just a few kilometers outside the city was a key factor in developing the public’s awareness of the cave. Charles Spang, who lived across the road from the cave, began to work with Harp to widen the cave’s appeal. They built a small park around the entrance with amenities such as a food and beverage stand, a covered pavilion that could be rented for events, a playground with a merry-go-round and croquet, a shooting range, and a “zip line” ride through the trees. Spang was a practical joker and stitched together a number of “dummies” which were put in strategic locations in the cave to scare unsuspecting visitors. Spang also began leading tours as well as undertaking frequent exploration trips with Harp, and his family and the Harps became close friends.

As word spread about the cave, it became a popular local destination. It was reported that “hundreds visit daily” and that it was a “source of entertainment for the younger set.” More and more events were held at the cave including dinner parties, sorority group trips, fish fries, and scout troops. On one occasion, the “Jolly Pals” club explored the cave and a portable victrola was brought in to provide music so that dancing could be enjoyed underground. On another occasion, the San Antonio Cotillion Club hosted a “mystery party” at the cave. A picnic was first held on the surface while the attendees were entertained by a “masked gypsy.” The members then explored the cave finding a masked fortune-teller to read them their fortunes.

Top: Arthur Harp and Charles Spang prepare for a fish fry, which were held for groups at Robber Baron Cave.

Bottom: Soldiers from a nearby base visit the cave and pose with Spang (in front).

Photos provided by Charles Spang Jr.

The cave gained local fame for a time and was occasionally used for public events and was visited by various celebrities. The cave was even featured in advertisements by the Reo Motor Car Co. to advertise their new vehicles. In November 1929, an Atwater-Kent radio receiver was carried into the entrance of the cave to demonstrate the quality of the radio in that it could receive stations at both “the highest and lowest spots in San Antonio” (having previously been taken to the top of the newly built Smith-Young Tower—now the Tower Life Building). Radios were very large at the time, and it probably barely fit in the entrance. This event was judged by a number of local celebrities including Earl Abel who would later start the well-known restaurant on Broadway. On another occasion, the cave was visited by the Albertina Rasch dancers, a famous troop, whose leader choreographed many of the well known Hollywood musicals of the day.

Harp would occasionally lead off-trail tours for science classes and other interested groups. Self-guided tours were available, and to keep people from getting hopelessly lost, Harp blasted shut many passages, thus limiting the cave’s extent to what is presently known. In an interview, Harp told about leaving groups in the cave, but then finding they had other plans:

At first I would leave people by themselves after they assured me they wouldn’t move, but when I came back they would be gone. Then I would have to start out to find them, and the girls would be crying and scared half the death and the boys glad to see me. They simply can’t resist prowling around…I lose a lot of time hunting them out. No, sir, I’ve got everything safe now. [9]

Not all passages were blasted at the same time. Some were kept open so that he and Spang could explore them. He camouflaged these passages by constructing artificial walls, plastered with cave clay, so they would appear to a wandering tourist as a natural cave wall.

Passage in Robber Baron Cave during the commercial period. Photo by Harvey Patteson.

The same passage today. Note the floor is more than a foot higher as a result of washed in silt and the dumping of digging spoils. Photo by Bennett Lee.

In October 1929, the Black Tuesday stock market crash ignited the Great Depression. By the early 1930s, public interest in the cave began to decline with the worsening economic conditions. About this time, Harp’s mother became ill and it became more difficult for him to manage the cave. These factors combined to result in the cave being closed around 1933. Harp moved back to his family’s hometown in Kansas never to return to San Antonio. Except for some concrete embankments on the edge of the sinkhole, an unattached cave gate, and some bolts and electric lines in the cave, all evidence of the cave’s commercial period was removed by the mid-1930s.

1950s: Neighborhood Expansion

Over the next 40 years, a battle was waged between the cave owners, trying to seal the cave for reasons of liability, and increasing numbers of neighborhood kids (as the city expanded to and beyond the cave), who were continually digging it open. A factor of the cave’s accessibility that worked for and against both parties was stormwater runoff into the cave. Over the years rains would periodically fill and wash open the entrance crawlway.

In 1938, the cave was briefly used to commercially raise mushrooms (having earlier also been used to incubate chicken eggs), and a shooting range was resurrected briefly for a series of tournaments. The cave was next heard from in the late 1940s when City officials evaluated it as a possible atomic bomb shelter.

In May 1950, Robber Baron Cave was sold to a developer known as Busby the Builder who created the neighborhood that now surrounds the cave. The lot in which the sinkhole is located cost approximately $100 at that time. The change in ownership didn’t stop local youths from visiting the cave. In fact, visitation only increased as attested by the rise in graffiti dating from the 1950s and 1960s due to the large influx of families into the area.

In 1961, seven youths were trapped in the cave by mud and water clogging the entrance crawl. After considerable effort to excavate the crawl, all but one of the boys escaped. The remaining youth was stuck, and the San Antonio Fire Department had to haul him out. In other “rescue” efforts in the cave, S.A.F.D. personnel would often find their “victims” enjoying the effects of drugs and alcohol.

1960s to 1990s: Cavers and Surveys

In the meantime, cavers had begun to discover and explore Robber Baron. As early as 1934, William Gray produced a map of the cave showing about 800 meters of passage. In the early 1950s, Gordon Danz, Bob Hudson, and members of the St. Mary’s University Speleological Society explored the cave. Two trips were made in 1962 to survey Robber Baron Cave. The first was on the evening of January 12–13. The party consisted of University of Texas Speleological Society members Eugene Blum, James Reddell, A. Richard Smith, and Peggy Walkington. About one week later, Reddell and Smith returned with Orion Knox. A total of 550 meters were surveyed on those trips and an additional 300 meters were explored.

Digging out the muck-filled entrance at the bottom of the sinkhole in the 1960s. Photo by Orion Knox.

From March 7 to June 19, 1969, Roger V. Bartholomew and Wayne Russell led members of the original San Antonio Grotto on the first major survey of the cave. They produced a fine map that showed 1061 meters of passage.

In 1976, the newly reorganized San Antonio Grotto undertook the resurvey of Robber Baron Cave with one of their primary objectives being to include as much detail as possible. Their search for detail revealed many small passages that had been overlooked in earlier surveys. This raised the total length to 1336 meters. Teeni Kern, Gary A. Poole, George Veni, and Randy M. Waters led that effort which lasted from December 11, 1976 to March 17, 1977.

Except for the survey efforts, the owner had for many years refused cavers access to the cave. In 1976, the owner granted access to cavers after the determined efforts of Veni and Waters and the San Antonio Grotto (SAG) to gate the cave using many hundreds of pounds of concrete, brick, and steel in October 1980. “No Trespassing” signs were also installed.

Randy Waters crawling through the first gate on Robber Baron. Photographer unknown.

Following the gating of the cave, SAG members felt an effective cave cleanup was finally possible. Years of teen-traffic had adorned the cave with the expected assortment and volume of trash, string, and spray paint. An article was placed in a local newspaper that the cave was gated and a cleanup would take place the weekend of January 17–18, 1981. Anyone interested was invited to help. The purpose of this invitation was to educate the local residents about the value of the cave, discourage their further use of the sinkhole as a trash dump, inform them about the gate, and invite them to call the San Antonio Grotto if they would like to see the cave. The cleanup was very successful, and most of the trash in the sinkhole was removed. Since that time, the cavers have held periodic trips into the cave that included local youths who would have otherwise tried to break in, saving a lot of wear and tear on the gate. Other work projects through the 1980s included efforts to remove some of the graffiti adorning the walls.

Trash filling the entrance sinkhole before the first major cleanup in 1981. Photographer unknown.

The gate was ultimately breached, however. A new, more substantial gate was constructed, which too was eventually breached. In 1990, a large, bunker-style gate was constructed at the top of the climb down into the cave that had six-inch-thick, reinforced-concrete walls and a thick steel gate with only a small opening to access the lock. This gate was finally successful in securing the cave. In 1995, the lot containing the cave entrance, which had been set aside during the 1950s development, was donated to the Texas Cave Management Association in appreciation of the work cavers had carried out on the property over the years. Since gaining ownership, TCMA has undertaken a significant restoration of the cave property, and occasionally continues the graffiti cleanup efforts within the cave. Robber Baron is now protected as a Preserve for its unique features and history.

Rumors and Mysteries Beyond the Breakdown

When the San Antonio Grotto began their project on Robber Baron Cave in 1976, an advertisement was placed in the San Antonio Express News asking for people who had been in the cave during its pre-commercial, commercial, and immediate post-commercial years. Information was obtained through interviews with many individuals, some of whom were closely involved with the Harps. Of special interest were rumors that had persisted throughout the years of underground rivers, lakes, and of a tremendously extensive maze beyond the cave’s present bounds. Given the stories that Arthur Harp had spread, it was difficult to determine what was really true. In this respect, the interviews were truly priceless.

Charles Spang lived across the road from the cave and was a frequent companion of Arthur Harp. Together they installed much of the cave’s electric lighting and explored beyond the cave’s present limits. One of the areas they visited was where Spang’s windmill intersected the cave a few hundred meters east of Nacogdoches Road. The main extent of exploration though, was to the southwest. In that direction, Harp and Spang found:

  • a pit that was too deep to explore;
  • a lake and a stream passage that Robber Baron connected to Holmgreen’s Hole, an extensive (but currently sealed) maze cave about 700 meters to the southwest;
  • and passages that they estimated had led them as far as Texas Military Institute, 3.2 km to the southwest!

Arthur Michael recalled a deep pit, possibly to water, beyond Popcorn Alley. Ray T. Dixon remembered that in 1927 the cave extended east, well beyond Nacogdoches Road, but its major extent was to the southwest. In that direction, about 100 meters beyond the Pavilion Room, was the “tunnel to the stream.” His estimated distance from the entrance to the stream was about 400 meters:

Go in about a quarter mile…step down four feet into a passage about 40–50 feet long where you crawl on your hands and knees…step down, turn right, and go 25–30 feet to reach the river.

Dixon claimed the river was “about 8 feet wide and 2 feet deep.” The river came out of one wall and went into the other. The 2.6 meter high and wide passage Dixon was in continued unexplored from the river’s far bank. Dixon also mentioned that he saw pinkish-white eyeless fish in the river. (The most productive wells and springs in the rock in which Robber Baron is formed are due to artesian waters rising along faults from the underlying Edwards Aquifer. Blind fish have been found in the Edwards waters and could account for those found in the cave.) To the left of the “step down” following the 12–15 meter (40–50 feet) crawl, Dixon explored 70 meters by climbing along the passage walls with a stream far below him. The end of that passage was not reached.

Ted Zettner provided the most compelling and verifiable account of the cave’s great extent. “The main part of the cave got blocked off,” Zettner stated, and to prove it he elaborated on one particular trip he made into the cave in 1925. On that trip, it was decided among his group to take as much string as they could carry (so not to get lost) and by using a compass they would set off in one direction as far as they could explore. The passages they were in led them a great distance to the southwest. Eventually they reached a steep mud slope down into a lake room. Like Dixon’s river, the lake had blind fish in it. Unlike the river, a water well pipe intersected the cave and the lake. Its pump on the surface could be plainly heard in the cave. Zettner and his friends played in the water and then left the cave.

In 1925, there was only one windmill in the direction Zettner’s group had been traveling. Fifty-one years later, Zettner pinpointed the well’s location at 1.4 km southwest of Robber Baron Cave. Upon exiting the cave in 1925, Zettner and company approached the farmer who owned the well to inform him of their discovery. The farmer replied, “So you’re the little bastards who muddied my water!” That day had been the only time the farmer pumped muddy water from his well. Connection confirmed.


In view of these tales, and others of construction teams that often broke into caves when that part of the city was being developed, the San Antonio Grotto began digging at various breakdown areas in the cave. The first major excavation site was in the Pavilion Room, but more and more interviews indicated the west end of the Lighted Passage was the main route to the river. In late 1976, Poole, Veni, and Waters were joined by John Cross, Jesse Hernandez, and Chuck Pautz in the first of many assaults upon what is now referred to as the “Mystery Breakdown.” Veni and Waters headed the effort, and, by 1981, 10 meters had been tunneled with the use of picks, shovels, hammers, chisels, and buckets.

Jackhammer assist in pushing the Mystery Breakdown. Photo by George Veni.

Digging in the cave has been a relatively safe venture due to the type of rock involved, the Austin Chalk. After collapse, this soft rock compresses and recompacts itself into a stable matrix of relatively uniform density and consistency. Unlike other rock types where digging in collapse primarily involves the removal of individual breakdown blocks balanced upon each other, the Robber Baron dig is more akin to carving a tunnel (its average size is 1.3 meters high and wide). Although some parts of the tunnel have been shored with pressure-treated lumber, it is mostly a precautionary measure. Since the tunnel was dug, only minor amounts of clay and rock have sporadically flaked off the ceiling.

In 1981, the cave’s owner became interested in extending the length of his cave. Late that year and in early 1982, he rented an air-powered jackhammer to assist in the digging effort. A portable air compressor was on the surface and over 100 meters of high-pressure hose connected it to the hammer at the Mystery Breakdown. Kurt L. Menking constructed two carts for transporting excavated material out of the tunnel. The motto of the dig was painted on the side of the carts, “Holmgreen’s or Bust.” So far it has been “bust”.

Randy Waters with the “Holmgreen’s or Bust” cart. Photo by Kurt Menking.

The first 10–11 meters of the tunnel were dug through a compact rock-clay matrix. The uncollapsed cave walls were also excavated and used as guides for where to dig. However, the jackhammered 2–3 meters seem to be in an area of major collapse, and the walls were temporarily lost. It appears that that portion of the tunnel is carved through a single large breakdown block. Vibrations from the street located above the Mystery Breakdown are believed to have added to the collapse.

Enthusiasm in the Mystery Breakdown dig effort had faded by 1983 as other exciting projects beckoned. In 1986, some determined fellow breached the Robber Baron gate by use of a portable cutting torch. In 1987, a new and stronger gate was designed and installed. With the new gate came new blood. James Loftin, who had explored the cave in the early 1960s as a teenager, renewed his interest in caving and began spending a lot of time and energy at the cave with his sons Scott and Timothy. They began digging at leads throughout the cave and found several small extensions, but nothing leading out of the maze. The most remarkable and admirable aspect of their work was in removing all the dirt and rock they dug from the cave to not clog-up or otherwise alter the natural appearance of the other passages. They hauled tons of material! But their efforts paid off, when, in late 1987, they dug to a wooden false floor—one of Harp’s trap doors, which led to a passage. Unfortunately, it was only 7 meters long and ended in collapse. Later, Loftin dug into a series of narrow tubes at the south end of the cave, and most significantly, into a crawlway that led to a narrow pit that dropped 15 ft to a new lower level of the cave, adding 85 meters to its length.

Since that then there have been a few sporadic efforts but no new discoveries were made until 2008 when a new generation of cavers led by Joe Mitchell, Steve Gutting, Mike Harris, Jill Orr, and others have renewed interest in extending the cave. By taking a more thorough approach and using modern tools such as small portable drills, borehole cameras, compiling leads, and analyzing more accurate computer-generated maps, they have been successful in digging into three previously unknown areas of the cave. Survey of these passages extended the length of the cave beyond the one-mile mark in 2012. Although none of these discoveries have yet proved to be the breakout connection, they have continued to spur interest in the cave and demonstrate that there is more out there yet to be found.

Is all the digging worth the effort? Multiply the amount of passage per area (about 1.6 km per 100 sq. m actually, but trimmed down to 1 km/100 sq. m to assume the passage density decreases beyond the breakdown although all reports say it doesn’t) by the area in which it has been explored (at the very least 1.4 km by 100 sq. m to Zettner’s windmill) and you get a cave at least 14 km long. A less conservative, but still reasonable estimate of density and area could put the cave over 50 km long! So to answer the question, Robber Baron Cave is potentially one of the longer caves in the world and therefore well worth the efforts expended.


Based on article, “The History, Legend and Continued Exploration by George Veni, originally published in the NSS News, Volume 47, No. 6, June 1989, pp. 133–138. Extensively revised and updated by Joe Mitchell, January 2013.

[1] “Huge Cave Found Under San Antonio”, El Paso Herald, September 2, 1910.

[2] “Mystery of Wonder Cave is to be Solved“, San Antonio Light, March 26, 1911.

[3] “Caves Near San Antonio, Rich in Legendary Lore“, San Antonio Light, September 25, 1921.

[4] “‘Lost’ Explorers Emerge From North Loop Cave as Rescue Party Underground“, San Antonio Light, October 6, 1922.

[5] “Exploring Caves Where Robbers Walked”, Dallas Morning News, June 23, 1929.

[6] Barnes, Charles Merritt, “Combats & Conquests of Immortal Heroes”, 1910.

[7] “Indian Tomb Yields Dead“, San Antonio Light, March 4, 1909.

[8] “Dry Agents Are Lost 3 1/2 Hours in S.A. Cave”, San Antonio Light, July 21, 1925.

[9] “Cave Here Made Doubly Safe”, San Antonio Express, February 19. 1925.

You can help Robber Baron Cave.

If you are interested in helping us protect and maintain this unique and special part of San Antonio, please consider joining Friends of Robber Baron or donating to TCMA to help maintain Robber Baron Cave Preserve.

Donations may be made online, or checks may be mailed to TCMA, P.O. Box 7427, Austin, TX 78713. Please indicate on the check that it is in support of Robber Baron Cave Preserve.