Cave of Hercules

The Cave of Hercules (Cueva de Hercules) is a subterranean Roman structure beneath the streets of Toledo, Spain, built around the second half of the 1st century AD. Featuring thick Roman concrete walls coated with waterproof opus signinum and a barrel-vaulted ceiling of fitted ashlars, it functioned as a water reservoir supplied by the aqueduct crossing the River Tagus. The site later supported Visigothic, Islamic, and Christian structures above, with the Church of San Gines standing over it until 1841. Archaeological investigations in 2004 confirmed its Roman origin, and it was restored for public visits in 2010.