Under the West Virginia part of Greenbrier resort lies the secret Greenbrier bunker, built in the '60s to protect the US Senate during nuclear war. It can hold 1,100 people, with bunk beds, showers
Explore the quiet catacombs under City Market in Indy. Originally Tomlinson Hall's basement, now closed for tours due to construction.
Explore Onondaga Cave in Onondaga Cave State Park for stunning stalactites and stalagmites. Don't forget a jacket—it's chilly year-round!
The California coast in San Luis Obispo County has cool caves, arches, and rocks. You can kayak in the caves, some are 30 feet deep! Look out for seals, otters, and dolphins.
In 1861, big storms flooded Sacramento for 45 days. People raised the streets and houses by 9 feet over 15 years to avoid leaving. the Sacramento History Museum gives tours of the old basements
In 1963, the Texas Highway Department found Inner Space Cavern while testing rock for a bridge. A drill broke through the cave's roof, revealing a cool underground world with pointy rocks
Explore Indiana Caverns, the state's longest cave since 2013. Take cave tours and kayak on an underground river. Keep an eye out for cave crayfish!