An underground city of salt.

Danish observation tower designed to look like a giant beer bottle.

Bored potato-guarding Nazis etched their thoughts onto a brick storage building in Copenhagen's Meatpacking District.

Swedish skyscraper with a 90° twist.

Old Danish castle immortalized in Shakespeare's Hamlet.

Belly up to the bar in Cowtown, don't forget to buy some boots.

Southern Italy's spinning top village.

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

The largest wine cellar in the world is a 150-mile network of underground caves near the capital of Moldova.

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

This indoor ski resort has a mountain contained inside a mall.

A preposterously luxurious hotel with gold-plated iPads, Rolls Royce chauffeurs, and a staff that trains by watching "Downton Abbey."

Climb to the top of the world's largest seated bronze Buddha.

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.

Founded as a refugee camp, now a popular tourist spot.

A Spanish town built into the cliffs.

The deepest sinkhole in Central Europe comes with a grisly tale and an unusual nickname: “The Stepmother Abyss.”

Europe's second largest ossuary wasn't discovered until 2001.

A former top secret nuclear fallout shelter now operates like a hotel stuck in the Cold War.

A peculiar clock commemorates a historic victory won by ringing the noonday bell an hour early.

This tipsy office building in downtown Prague was originally called “Fred and Ginger.”

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

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