An underground city of salt.

Poland's oldest surviving university building holds a wealth of historic science instruments including some used by Copernicus.

Real bones which are said to have belonged to a Polish dragon.

A museum dedicated to a secret military hospital hidden beneath a castle in Budapest.

The mummified right fist of a 1,000-year-old saint-king sits inside an ornate golden reliquary.

From Austrians to Nazis to Soviets, this historic Budapest fortress has a history as complex as the city itself.

Built in 1870 at the bridge that connected Buda and Pest, this spectacular incline railway was almost lost forever during World War II.

A trail of iron footwear stands as a monument to the thousands executed along this riverbank during WWII.

This exclusive resort has completely covered a tiny Balkan island in a 5-star warren of guest rooms.

The iconic boulevard is the perfect place to catch sight of a bicycling skeleton, a levitating Satan, or a chef with his head stuck in a pizza.

Gaudí's famously flamboyant architectural style is on full display in this sprawling park and garden.

One of Antoni Gaudí's most classic buildings is well-known for its "dragon-back" design.

Construction of Barcelona's iconic (but controversial) church is expected to be completed in 2026—a century after the death of its architect.

Water and windows define this defensive Italian well.

Pilgrimage site for star-crossed lovers.

Yo, Adrian!

Four glass boxes hover over 1,000 feet in the air to give visitors an unparalleled view of Chicago.

This historic timepiece is thought to be the only public clock in the world that keeps lunar time.

A number of craters left by fatal mortar strikes have been filled with red resin to remember those lost during the Siege of Sarajevo.

Oriental bazaar in the heart of Sarajevo.

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

Bridge that died in war and was resurected.

A narrow passage next to a cafe leads to a courtyard exploding with murals, tags, and paste-ups.

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