The Subterranean World Heritage List, a subset of the UNESCO WHL.
Cave Castles, a very special usage of natural caves: to build castles inside.
Dragon Caves. Or do you not believe in Dragons?
Bears' Caves, the home of cave bears.
Caves Used as Road Tunnels, or sometimes railway tunnels.
Cave Visits By Tram.
Gypsum Caves and Mines, all sites related to gypsum.
Caves With a View, have a look!
Blue Grottos, sometimes green...
Cave Trekking Tours aka wild caving with a guide, where you can do a little caving yourself.
Caves with Paintings, which are open to the public.
Cliff Dwellings of the U.S. West