Underneath this Byzantinian church lies a necropolis filled with ancient tombs and the ruins of previous churches.

A striking symbol of the Bulgarian capital.

Erotic art covers the walls of the largest ancient pleasure palace.

Before it was buried by volcanic ash, this fast-food restaurant fed the hungry hordes of ancient Rome.

For centuries, this large Roman villa remained hidden thanks to the eruption that buried nearby Pompeii and Herculaneum.

Italian cave with exceptional acoustics and an unsavory history.

Over the centuries, this island paradise has done it all, from providing monks with ecclesiastical respite to sheltering an exiled Leon Trotsky.

One of the largest wooden constructions in Europe was meant to be a casino, but soon became an orphanage.

Ancient serpentine sacrifice holder that has stood the test of time.

A gorgeous, Gaudí-esque stairway constructed in the city of Istanbul by a prominent Jewish family.

This remarkably well-preserved Egyptian plinth is pretty well traveled for a giant piece of stone.

A Lycian city of the dead carved into the hillside of Southern Turkey, complete with startlingly human touches.

A small etching on the white marble parapet was written in runic script by a Viking mercenary.

Roman ruins top white travertine terraces formed by ancient hot springs.

In this historic region, homes and churches are carved into ancient volcanic rock formations.

While not Turkey's deepest underground city, this subterranean redoubt is the largest.

Roman ruins, natural methane fires and a lovely beach.