The Devetashka cave in Bulgaria is one of the most beautiful karst caves in the world. Running water and protection led people of the Paleolithic Period into the safe haven the cave provided. The cave was rediscovered by a Bulgarian scientist in 1921 but it was not fully excavated until the 1950s when there were plans to make it a giant warehouse. In the 1950s, Devetashka Cave was used as a military site and for the storage of petroleum, which destroyed some of the natural formations in the cave. Archaeologists have found some of the most important prehistoric finds in Bulgaria in the cave, especially their discoveries from the Neolithic period. Now, twelve species of protected amphibians, eighty-two bird species, thirty-four species of mammals, and fifteen species of bats routinely make the shelter home. In fact, some 30,000 bats are said to live there. Seven holes in the ceiling provide the location with ample light and a great environment for lush greenery. Add beautiful stalactites and stalagmites, rivulets, and majestic natural domes, and one can easily imagine why various human populations would have chosen Devetashka as their home over the years.