#1 Mammoth Cave (Kentucky)
With 400 miles of excavated caves, this UNESCO World Heritage Site has the longest cave system on the entire planet. The year-round selection of beautiful routes includes both professional and self-guided trips, with levels of difficulty ranging from fairly straightforward to extremely challenging.
Each of the many guided tours covers a few of the cave’s most recognizable features: you can visit the underground river on the River Styx Tour, explore rock formations that replicate Gothic buildings on the Gothic Avenue Tour and wander by torchlight alone on the Violet City Tour.
Bonus: If you visit during a storm, you might even notice a layer of mist forming inside the cave. Very eerie.
Tour availability varies by season. Children’s tickets cost $9, while adult tickets are $11.
