A monumental underground karstic wonderland is also the water source for over a million citizens of Beirut.

Beirut's thinnest building was the result of feuding brothers.

Only a handful of these gorgeous historic waterwheels remain but even those are in danger from local unrest.

This ancient mountain monastery welcomes all manner of faith in an effort to keep Christians in Syria.

Amid the rubble of Aleppo's Old Quarter, part of a historic market has been restored and re-opened.

One of the oldest and largest castles in the world.

Ruins of the Crusaders' headquarters.

Mysterious lost empire of the Silk Road.

This abandoned Soviet circus is slowly being restored to its Communist-era glory.

This 13th century Orthodox monastery is built right into the Moldovan cliffside.

This sign marks the entrance to a tiny proto-state within the small country of Moldova.

Seventy-five miles of limestone caves host more than a million bottles of wine beneath a sleepy Moldovan town.

A forgotten remnant of the Soviet Union, Transnistria is an unrecognized country hidden behind a heavily militarized border between Moldova and Ukraine.

A monument to the three wars that led to German unification towers within a Berlin traffic circle.

These former Nazi anti-aircraft towers offer a singular view of the north of Berlin in the summer, and a sanctuary for bats in winter.

Thousands of coffin-like pillars make up this controversial Holocaust memorial.

A glacial pothole was once a hideout for a notorious Scottish outlaw.

Where the sleeping monsters of Scotland's oil industry are left to rust.

A sea cave with a waterfall and Viking past

Accessible only at low tide, the deserted island is dotted with World War II ruins.

Possibly the world's largest hourglass only needs to be reset every New Year's Eve.

This sculpture honors the man who was known as the "Righteous Among the Nations."

The metal leaves on this tree are engraved with the names of Holocaust victims.

A statue in Budapest's Liberty Square honors the former U.S. president's efforts to end the Cold War.