One of the most easily accessible examples of the rare 1960s UFO houses.

This magnificent museum claims to house the cranium of a disciple and the skull of a pope.

Daily jousts and dancing barrel makers in Munich's mechanical clock.

Giant WWII fortresses that fired 8,000 rounds a minute, now home to thousands of pigeons.

This series of Baroque passageways in Vienna's cultural center mix old architecture with modern art.

A rooftop restaurant hides in plain sight atop Vienna's Palace of Justice.

The Habsburgs' royal collections of art and wonders.

This museum preserves the hand-dug tunnel that kept Sarajevo afloat during the Serbian siege.

A war-torn Olympic relic is being overtaken by graffiti and nature.

Oriental bazaar in the heart of Sarajevo.

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

A 11-foot former president stands on a Kosovo street that also bears his name.

This ancient theater, restored in the 20th century, lives on as a venue for dramatic and musical performances.

A gigantic statue of a Russian soldier watches over the ancient city of Plovdiv, a prominent reminder of the Soviet period in Bulgaria.

This Arabesque Italian castle was built with a primitive, if ingenious, air-conditioning system.

Why a column on the entrance is inscribed with a verse from the Quran is one of Sicily's many mysteries.

Every inch of this chapel is covered in craftsmanship from across the world.

The world's most active stratovolcano is almost always erupting.

142 ceramic steps become a mosaic once a year.

Italian cave with exceptional acoustics and an unsavory history.

Two stone columns flank the grand Venice square, but there were supposed to be three.

The only museum with its curator—and her pets—buried inside.

Dinosaur eggs were first discovered at these fiery red cliffs.

2300-year-old Roman road connecting the empire.