Italian cave with exceptional acoustics and an unsavory history.

The world's most active stratovolcano is almost always erupting.

This innocent-looking townhome is actually a subway exit.

A small side chapel in Santa Fe's basilica is home to the oldest statute of the Virgin Mary in North America.

Like stepping into a spooky fairy-tale, this shop carries the dark ideas of artists and other makers.

This statue intended for children to enjoy became a minor political spat.

The winding route passes through an enclosed alleyway, two tunnels, and leads to the White House basement.

Long-abandoned trolley tunnels just a mile away from the White House are turning into an art space.

This unacceptably tall building was the real reason for Washington, D.C.'s skyscraper ban.

The ruins of an ancient mansion sits in front of and underneath a contemporary art gallery.

A crushed gate and giant bronze head serve as a reminder of Greece's fight for freedom.

There are many Byzantine-era churches still standing in Athens, but this is the only one with a 2,500-year-old column rising through its roof.

The Cycladic architecture makes this Athens neighborhood feel like an island paradise hidden in the shadow of the Acropolis.

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

The ruins of an ancient Roman tomb hidden in the basement of a trendy clothing store.

This ancient hydrological marvel is now the base of a modern outdoor cinema.

Large collection from the 3rd millennium BCE.