A geological oddity topped with a 2,000-year-old pagan temple.

This Armenian monastery was carved out of cliffs and named after the spear used to stab Jesus.

Monasteries on rock pillars, once accessible only by frayed ropes.

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

A 2,000-year-old computer demonstrates remarkable engineering and astronomical precision.

Where commuters walk through remnants of an ancient Greek necropolis.

Step back in time and witness the fall of Constantinople.

A marvel of Byzantine engineering under the streets of Istanbul.

1513 Turkish world map, full of European state secrets and snarky commentary.

Budapest's Communist-era statues, banished to the suburbs.

Lithuania's outdoor sculpture trail of wooden folk art.

Flamboyant architecture from the turn of 20th century.

An old hill fort covered in over 100,000 crosses is a symbol of Lithuanian nationalism and beliefs.

3,000 market stands in five former Zeppelin hangars.

Metro station with a claim to rock n' roll fame.

Cold war icon and onetime "hole" in the iron curtain.

The most visited, and possibly most controversial, museum in Germany.

Thousands of tourists and residents in Cologne affix "love padlocks" on the Hohenzollernbrücke Bridge to symbolize their affections.

Incredible labyrinth of man made caves.

A little sculpture with a large wardrobe.

Three floors of musical instruments coming from all corners of the world and hundreds of years of musical history.

Christ's blood allegedly preserved in a Belgian town.

Colorful and chaotic stacked hotel in North Holland.

Museum preserving torture methods from the past.