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

The remains of Crystal Palace Great Exhibition of 1851.

Gargantuan home of Russian science.

A giant bronze monument to Kim Il-sung and Kim Jong-il is one of the most sacred sites in North Korea.

The final resting place of the great navigator, or maybe his brother.

Three bridges and one giant canyon make up this fantastic Spanish settlement.

While not Turkey's deepest underground city, this subterranean redoubt is the largest.

A wooden replica of France's famous tower.

Stalinist skyscraper built with help of cryotechnology.

The modern birthplace of Irish freedom.

The tiny Belgian town's ancient version of Mardi Gras involves eerie wax masks, sticks for warding off evil, and ostrich plume hats.

This sprawling concrete suburb of Kraków was designed by the Soviet Union as the model proletarian city.

Want to properly offend a king? Sculpt a giant hill figure in chalk of him riding out of town.

London's last remaining public soapbox site has seen speeches from Karl Marx, Vladmir Lenin, and George Orwell.

A "simple-hearted artist" turned an isolated Icelandic valley into his own art museum.

The largest bell in the world has been swinging high above a Cologne cathedral for almost a century.

The rotting skeleton of a shoreside fun fair that was destroyed by fire and storms still haunts the Brighton ocean view.

Beach instrument turned bed and breakfast.

Ancient serpentine sacrifice holder that has stood the test of time.

One of England's most famous churches hides a pair of little known architectural treasures.

This well-preserved Cistercian Abbey in a romantic pastoral setting has inspired artists like the poet Wordsworth.

A particularly disconcerting tribute to Irish martyrs.

A phallic shrine to a princess goddess in Krabi, Thailand.

A statue in the heart of Edinburgh honors a bear that served in the Polish military during World War II.