This abandoned shopping arcade has new life as an art installation.

View the ancient remains of buildings and the ancient "River of Hades" before hopping on a train.

An intricate network of underground tombs carved into volcanic rock.

One of the best-preserved medieval streets in Europe.

Dedicated to the god Dionysus, this theatre was used for both musical and theatrical performances.

A sprawling collection of books and manuscripts about ancient Greece that would have put their famed libraries to shame.

A Byzantine-era church hidden in a wooded area below the Acropolis.

This field of half-buried stone crosses was the burial place of a sect of heretical gnostics.

This 200-meter-high waterfall marks the site of Achilles’s immortal baptism at the mouth of the River Styx.

This gem is often wrongly overshadowed by the larger, newer Metropolis church in Athens.

Where commuters walk through remnants of an ancient Greek necropolis.

Hideout of thieves, monks, and goat-footed gods.

Legend says this sacred tree was a gift from goddess Athena.

The oldest cemetery of modern-day Athens blends the modern and ancient worlds.

Giant marble phalluses on the sacred island of antiquity.

This legendary city has been a tourist attraction for centuries.

Hidden in a secluded Greek cove is a pristine beach marred only by the rusting smuggler's hulk stranded on its shores.

Inside this building is another country within Rome, a sovereign entity without a physical territory.

This ancient Roman arch misled treasure hunters for centuries.

Remnants of a 4th-century church with vivid medieval frescoes and ancient sarcophagi hide beneath this old basilica.

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

Ancient ruins hidden underneath a modern luxury hotel.

A mysterious chasm in the heart of the ancient Roman Forum, the Lacus Curtius was once believed to be a gateway to hell.

One of seven Jewish catacombs in Rome and one of only two open to the public.