The difference between Ohio’s crystal cave and other, more mundane varieties may not be apparent—at first.

But in the Crystal Cave, you are not in fact inside a cave but wandering within a single rock: It is the world’s largest geode.

The geode was discovered in 1887, by workers digging a well for winery operator Gustav Heineman. Heineman found that the formation was in actuality a “vug,” or large cavity within a single rock. It took its name from the three-foot-long Celestine crystals jutting from the walls, many of which have been mined in order to be used as fireworks. As a result, the cave is likely less beautiful today than it once was, though it is also roomier, and many of the crystals remain in place.

Though the setting—the world’s largest known geode, studded with crystals—is hard to beat on its own, you may as well take advantage of the accompanying Heineman winery tour, and explore the crystal cave with a bit of a buzz.