The only surviving choragic monument is a trophy awarded in 334 BC for the winning dramatic chorus.

An intricate network of underground tombs carved into volcanic rock.

These artifacts were discovered during the construction of the airport, with some dating back to the Neolithic period.

These caves secretly held national treasures during World War II.

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

This small 16th-century church in Athens is almost entirely surrounded by a modern building.

Heralded as the world's first theater, these ruins are often overlooked as they reside in the shadows of the Acropolis.

This mystical orb covered in strange symbols is thought to have been used in ancient Greek magical rituals.

The railway carts travelers to central Athens's highest peak, which offers stunning vistas of the city.

This ancient Greek place of assembly and marketplace is being revealed layer by layer below the modern Athens cityscape.

An architectural oddity hides in plain sight on this iconic London bridge.

A historic London cemetery now serves as a nature park incorporating gravestones & memorial statues.

Six ravens are kept captive (but well-fed) at the Tower of London to prevent the fall of the Crown.

Created as a "model concentration camp" to hide Nazi atrocities from the international community, this former camp-ghetto now holds a museum and memorial honoring the lives lost within.

This walkway is so narrow it needs its own light to stop pedestrian traffic jams.

An eerie, existential museum dedicated to the author of "The Metamorphosis."

A bust of Franz Kafka spins in pieces, reflecting the writer's inner torment.

Around 100,000 bodies are buried below the medieval headstones, many of which mark graves with multiple bodies stacked up to 12 deep.

A neo-Gothic church built to thank God for saving the Emperor of Austria from an assassination.

Legends surround an ancient tree trunk riddled with nails for good luck.

A silly medieval mural preserved on the side of a Viennese house.

Swarovski's museum/theme park is a fake diamond fantasia overlooked by a giant.

Trick water gardens from 1619 featuring a 200 piece mechanical theater powered by water.

Op-art architecture designed for happiness.