Longest fortress system anywhere in Europe.

The place where World War I began.

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.

This one-time health resort was used by aristocrats around the world.

Built to give thanks for the passing of a plague epidemic, this cathedral is a one-of-a-kind architectural hybrid.

The yawning maw of this pagan visage is said to bite off the hands of liars.

Dublin's most modern, visually spectacular bridge is modeled after Ireland's national emblem.

A 1,215-foot tunnel transports pedestrians beneath the River Thames.

High atop the Eiffel Tower is a small apartment built exclusively to entertain the science elite and make the rest of Paris jealous.

The de facto symbol of Copenhagen is this bronze fairytale which cannot seem to keep its head for very long.

These slanted cubic abodes are a creative if odd solution to a zoning pickle.

This fairytale castle was built as a show of power but was nearly torn down thanks to its history of torture.

This group of small islands on Lake Nicaragua formed after an eruption of the Mombacho volcano.

This massive Maya archaeological site is home to the tallest man-made structure in Belize.

This stunning mass of ice spans 121 square miles and is still growing.

What was once a unique system of urban elevators is turning into a mechanical ruin.

Teeming with illegal goods and services, this towering maze of vice is also a popular tourist accommodation.

"There's nothing there," and other lies the KGB told us.

A black cat protests the City Guild in Riga's Old Town.

3,000 market stands in five former Zeppelin hangars.

This former KGB building is now a museum memorializing the people who suffered during the Soviet regime.

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

This Slovak bridge is known both for its connection to a national uprising and its UFO-shaped eatery.