Poland's oldest salt mine has nearly everything one needs to live underground forever.

A controversial artwork draws attention to the dark history of Prague's "Suicide Bridge."

A saintly relic hidden in a Prague church basement.

A gift from Emperor Franz Joseph I to his wife.

An ornate private entrance to the Vienna subway built specifically for the emperor.

The topiary maze at the Habsburg hunting lodge.

An abandoned 19th-century iron factory perched along the outskirts of an idyllic village.

This picturesque castle in Poland has a rich history, including a legend that ties it to lost Incan treasures.

The ruins of a 13th-century monastery that long served as a place of refuge from wars and raids.

A gorgeous stone viaduct crosses over a bucolic valley.

On Gellért Hill, this statue depicts the tragic tale of lovers divided by the Danube.

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

Once the home of a hermetic monk, this cave now houses a small church.

Budapest's Communist-era statues, banished to the suburbs.

When a supermarket opened up shop within a medieval building it became protected by UNESCO on a technicality.

The big toe of this towering monument to a Croatian national hero is worn from years of superstitious rubbing.

The complex has been abandoned since the Croatian War of Independence, barring a stint as a set for 'Game of Thrones.'

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

This Croatian island is for sale but no one is buying due to the dozens of accused Nazi sympathizers who were massacred there after WWII.

These historic defenses ensured the city within would survive hundreds of years of occupations, sieges, and invasions.

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

This museum in the famously blue neighborhood of Sidi Bou Saïd showcases a traditional Tunisian lifestyle.

Some believe this abandoned Brutalist masterpiece inspired George Lucas's Sandcrawler.

These excavated burials from the Tarim Basin are wrapped in mystery.