Zigzagging in a rocky, muddy labyrinth for more than a mile under the Northwood neighborhood, the Robber Baron Cave is the longest and most storied of some 500 caves in Bexar County.

For one day every 18 months, the public has the opportunity to explore this urban “wild cave” in North Central without the usual guides and lighted trails, equipped only with sturdy shoes, light helmet, gloves and wearing old clothes you won’t mind getting dirty.

A popular tourist attraction in the 1920s and a speakeasy during Prohibition, Robber Baron Cave has been owned since 1995 by the Texas Cave Management Association, which will hold a free open house from 9 a.m. to 3 p.m. Nov. 11.

The cave is a mile south of Northeast Loop 410 at Nacogdoches Road and the aptly named Cave Lane.

Joe Mitchell, cave manager, said spelunking — or cave exploration — has aspects of an extreme sport, but serious cavers are more interested in the intellectual challenges.

“Good athletic skills are needed to reach some passages, but this cave doesn’t require rappelling and can be experienced by just about anyone. On the scientific side, amateur cavers are involved with mapping caves and saving them because there aren’t many professional scientists who are paid to do it. Caves are easily damaged and need protection.”

The cave is a wonderful place to go spelunking, another enthusiast said.

“Robber Baron isn’t the prettiest cave, but it’s a great place for people to explore and learn about the underground environment,” said Michael Harris, the assistant cave manager. “People should think of it as an underground hike. The most important thing is to wear sturdy shoes. Flip-flops won’t cut it.”

Make that a hike plus a hardy obstacle course. You often have to stoop, crawl or work your way through crevices in the rock. The uneven passageways meander in confusing ways, but maps are available on paper and T-shirts; those sales help to maintain the preserve. Donations also are appreciated.

Mitchell, a laser-optics engineer at Southwest Research Institute, and Harris, a retired law-enforcement officer, are members of the San Antonio Bexar Grotto, a local caving group affiliated with the National Speleological Society. Volunteers from the Grotto, which has about 60 members, help maintain the Robber Baron and will be on hand to assist newbie cave explorers.

Presentations by the Edwards Aquifer Authority and Bat Conservation International, a Cheesy Jane’s food truck and on-site portable toilets will be new to this year’s Open House. Also, a photographer will take pictures of visitors and printed photos will be available on the surface. Helmets and gloves are provided. Participants must sign a release form.

Mitchell expects about 500 people to tour the cave.

“This is a fun cave for people to see on their own,” Mitchell said. “Two endangered species are thought to live in the cave. I often see the Robber Baron Cave Mesh Weaver, a type of spider, but the Robber Baron Cave Harvestman, a troglobite usually called a ‘daddy longlegs,’ hasn’t been spotted since the late 1980s. However, about 70 bats live in the cave, which is up from only about 10 a few years ago.”

Known at least since the early 19th century and once called the Cave of the Quebrantahuesos (Spanish for “vulture” or “bone-breaker”), Robber Baron probably has a geologic origin related to the Edwards Aquifer, but it’s in the Austin Chalk limestone formation.

George C. Saur bought the cave in 1910. Then years later, he hired Arthur Harp to develop the cave as a tourist attraction. Harp made up a story about it being an outlaw hideout and coined the name “Robber Baron” to make it more mysterious. With a hot dog stand, merry-go-round and cable ride, the cave attracted some 300,000 visitors over a decade. During Prohibition, Maggie’s Den had a door with a peephole and served as a speakeasy, though a raid by dry agents in 1925 failed to find any evidence of bootleggers.

Saur sold the cave in 1950 and it suffered neglect until the San Antonio Grotto cleaned it up beginning in the 1970s. Today, Robber Baron is protected as a karst resource to preserve its unique biology, geology and history.

To tour the Robber Baron Cave during the open house, visitors can just show up and tour the cave on a first-come basis. Or, you can sign up in advance for a self-guided tour for specific times and skip the lines. Also, reservations can be made for small-group guided tours to off-trail locations, restricted to ages 12 and up.

Sign up on the TCMA website,

The Bexar Grotto meets at Chester’s Hamburgers, 1006 N.E. Loop 410, near the Robber Baron Cave. Memberships, $5 per individual or $6 families, are open to anyone. For meeting times and information about caving trips, search for the Bexar Grotto at


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