Austria's ultra-modern art museum looks like Cthulhu's giant alien heart.

The world's largest historic armory was established by independent citizens to defend themselves from the wars of larger forces.

Rock-hewn monastery complex with hundreds of cave structures tucked away into the mountainside.

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.

The world's longest outdoor covered escalator system transports commuters through Hong Kong's hilly terrain.

Remnants of the most densely packed city in world history, that thrived on anarchy for 30 years.

The most famous location in China was home to whole dynasties worth of imperial rulers.

The deepest metro station in the world.

340-foot statue built to honour the Heroes of the Soviet Union.

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

A beautiful mountaintop mausoleum devoted to a Montenegrin icon can't seem to make everyone happy.

Longest fortress system anywhere in Europe.

These warring psychedelic crags commemorate an unsuccessful military operation.

There's a mini version of Iguazu Falls hidden in the Balkans, and it's got a rope swing.

An apparition of Virgin Mary in Herzegovina.

Bridge that died in war and was resurected.

This top-secret nuclear bunker hidden in a Bosnian mountain has been converted to a modern art exhibition space.

Oriental bazaar in the heart of Sarajevo.

This historic cemetery was inaccessible for several years due to dozens of land mines.

The remains of the last Bosnian fortress to fall to the Ottomans are still standing.

Where the lovelorn find a home for their sentimental keepsakes.

Croatia's towering concrete blossom grows from the site of a World War II concentration camp.

This stunning, out-of-the-way Croatian monument commemorates a community's uprising against occupying fascist forces.