Elevated freight railway turned wildly successful urban park.

Giant topiary dog once played a role in a terrorist bomb plot.

Historic medieval fortified city in southwest France.

A chain of 16 wondrous lakes formed as a result of the gradual dissolution of soluble layers of bedrock.

A musical instrument played by the sea.

Built by a king and rebuilt by an emperor, this aqueduct transported water for 1,200 years to this ancient Mediterranean hub.

A stunning mosque owes its design to an Ottoman ruler nicknamed "the Butcher."

A massive, heart-shaped, wind-carved crater in the middle of the Israeli desert.

Squeezing inside this deep, narrow canyon reveals a festival of desert colors.

This daunting 1st century fortress was purportedly the site of one of the most dramatic revolts of the Jewish-Roman wars.

The bluer than blue waters in these natural Israeli caves are reached via the world's steepest cable car.

This monumental work of art symbolizes the coming together of a previously divided city.

An imperial church bombed to ruins during WWII now stands as a jagged memorial.

Metro station with a claim to rock n' roll fame.

A 12th-century fortress containing some of Berlin's oldest buildings.

On the Spree bank, discover one of the last reminders of a symbolic wall that divided, and was torn down by the people.

A fascinating insight into daily life in the Eastern Bloc.

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

This lesser-known Frank Gehry building houses a treasure trove of cinema history.

Former hunting lodge of a duke who was an avid collector of impressionist works.

The tradition of open-air secondhand and antiquarian bookselling in Paris dates back to the Renaissance.

The ruins of a Duke's bucolic dream, where camels once roamed alongside "Dutch" windmills and faux-Italian vineyards.

An "inside out" building in the historical center of Paris, featuring Europe’s largest modern art museum.

Notorious artist squat renovated into legal studios.