The world's second-largest sundial, made entirely out of stone.

The birthplace of Karl Marx is now a museum dedicated to the communist revolutionary's life and work.

An imperial fortress city that incorporated cultural elements from the entire Mughal empire, only to be abandoned the year it was finished.

The tallest hotel in Europe.

In 1943 the British military took control of this village, telling residents they had to leave temporarily. The villagers were never allowed to return.

Children's hospital in London that operates on royalties received from Peter Pan, which J.M. Barrie signed over in 1929.

Regency-era excess on the English Coast.

A Victorian park cemetery, standing on the site of what was once the Great North Wood.

Eighty million natural history specimens call this gargantuan museum home.

Man-made cave with enigmatic carvings, some say made by the Knights Templar themselves.

Giant, friendly pelicans in Central London, the most unlikely of places.

One of the oldest and certainly best preserved Cistercian abbeys still in existence.

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.