A burial vault located under Tiber Island in the middle of the Italian capital.

This small church was constructed over the ruins of three temples dating to the Roman Republic.

In the early Roman Empire, people deemed traitors and criminals were tossed to their deaths from this rock.

The ruins of the largest gladiatorial school in Rome are largely hidden under modern streets.

This small Roman arch was transformed into a dwelling by the founder of the Trinitarian Order.

A fortified medieval basilica on the Caelian Hill preserves extraordinary frescoes and one of Rome's most beautiful hidden cloisters.

An alchemist's "magic door" stands in the middle of a Roman park.

Its interior is adorned with some of the best examples of early Christian mosaics.

This Roman arch marks the location of an ancient gate at one of the Seven Hills of Rome.