The Hercules Caves of Tangier are a series of caves in the Sahara Desert, located in northwestern Morocco. They are considered one of the most important paleontological sites in Africa and Europe.
The Caves of Hercules in Tangier were formed by the collapse of a roof that gave rise to a subway river. The river has been dry for about 4 million years, but it was still able to produce stalactites and stalagmites. It is estimated that there are more than 1,300 caves and passageways spread over an area of approximately 1 square kilometer. The caves are considered a natural wonder and a major tourist attraction.