Longhorn Cavern is a spectacular natural wonder in the heart of Texas Hill Country. It’s an underground labyrinth formed eons ago when a rushing river sculpted the limestone bedrock. Left behind are gravity-defying rock formations, dazzling crystals, ancient fossils and an anthology of folklore. You’ll see and hear it all at Longhorn Cavern State Park in Burnet, TX.

But first, what’s the difference between a cave and a cavern?

The words are used synonymously, but there are complex geologic distinctions we won’t get into here. Generally speaking, a cave has a primary chamber entered through an opening in a hillside or cliff. Caverns tend to meander below the earth’s surface with passageways that connect multiple chambers. I didn’t know any of that until I looked it up.

Longhorn Cavern was named a National Natural Landmark in 1971. To explore its depths, you have to join a guided walking tour. (There’s a charge, but admission to the park is free.) The entrance is at the bottom of a zig-zagging stone staircase, and that’s where you’ll meet your guide. For the next 90 minutes and mile-and-a-quarter trek, he or she will lead you through the various chambers.  You’ll learn about their unique features and the people who found shelter among them. Like these:

• Crystal City is an awe-inducing chamber aptly named for the glittery calcite crystals that blanket the walls and ceiling.
• Confederate soldiers made gunpowder from the ample supply of bat guano they found within. Keep an eye upward–you might spot a tiny furry bat clinging to the ceiling.
• The infamous Texas outlaw and train robber Sam Bass is said to have hidden $2 million in gold somewhere within the intricate network of tunnels and offshoots. If the treasure exists, it has yet to be found.
• During the Prohibition Era, the cavern was used as an illicit speakeasy and dance hall.

Be prepared for some geology humor from your guide. Here’s one: What did Sherlock Holmes say when he came to Longhorn Cavern? It’s sedimentary. Ha ha.

If you’re really adventurous, you can wriggle, climb and crawl through the undeveloped lower level of the cavern on the Wild Cave Tour. You will get dirty and wet. Saturdays only.

If you prefer a more leisurely pace, you can hike the nature-laden trails, spread a picnic lunch and tour the museum of 1930s-era architecture and artifacts. The park is a daytime park, 363 days a year, so there’s no camping or overnights.

The State of Texas bought the property from a former cattle rancher who raised longhorns; hence, the name. The park was developed in the 1930s by the Civilian Conservation Corps, a federal work-relief program formed during the Great Depression. The park officially welcomed the public in 1938.

Longhorn Cavern State Park

6211 Park Road 4 South

Burnet, TX 78611

(Thank you to Longhorn Cavern State Park for hosting my visit–and to our great guide, Cosmo!)