St. Michael's Cave is a network of limestone caves located in Gibraltar's Upper Rock Nature Reserve and known for its stunning stalactites and stalagmites.

The cave was long believed to be bottomless. This probably gave birth to the story that the Rock of Gibraltar was linked to Africa by a subterranean passage under the Strait of Gibraltar. During WWII the cave was prepared as an emergency hospital, but was never used as such. The cave makes a unique auditorium for concerts, ballet and drama, with capacity for 600 persons.