Once the fallout shelter of a dictator, this sprawling bunker is now a combined history museum and contemporary art gallery.

An Albanian monument to the Communism that nearly crushed the country is now a crumbling wreck.

This Slovak bridge is known both for its connection to a national uprising and its UFO-shaped eatery.

This fortress dates back to the 6th century and is also the site of a controversial abandoned restoration project.

A striking symbol of the Bulgarian capital.

"Holy Wisdom" overlooks the city that became its namesake.

This massive collection of British military artifacts includes the heartbreaking personal letters of the men in the trenches of WWI.

An unusual round church in London with a Templar past.

A Bulgarian monument to Russia's role in World War II is constantly being painted in pop culture protest.

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

A vast Communist-era exhibition space in the Bulgarian capital.

Destroyed Serbian army headquarters sits half crumbled in a largely revitalized Belgrade.

The old observatory in Copenhagen has a spiral corridor used as a racetrack.

After funding was cut for a memorial to the Danish author, the sculptor had his statue ceremonially lowered into the city harbor.

A pair of connected skyscrapers form this symbolic gateway.

A small memorial to a deadly night in Serbia that shook the world before it was swept under the rug.

This now abandoned restaurant provides some of the most amazing views of Lisboa.

Some call this eerie forest of crooked trees the "Bermuda Triangle of Romania."

This Transylvanian church has changed its denomination four times.

A fire once nearly devoured this gorgeous 14th-century Gothic cathedral.

The European towns of Brașov and Râșnov each have proud signs reminiscent of the Hollywood sign.

An ancient knight and a symbol of the city's freedom.

This once architecturally advanced housing complex is now a haven for squatters that still bears the scars of war.

These caves secretly held national treasures during World War II.