Famed Ancient Baths of Caracalla
Ancient Romans have a well-deserved reputation for building incredible structures, above and below ground. Now, thanks to an in-depth restoration, visitors can walk through more of those structures - the subterranean tunnels under the historic Baths of Caracalla in Rome. The baths were built between 212 and 216 AD during the reign of Emperor Caracalla, and were the second-largest ever constructed by the Roman Empire. The complex was powered by a nearly two-mile-long network of pipes and a nearby aqueduct that supplied around 18.5 gallons of water per second.