An 800-year-old island castle in Guernsey's main harbor.

An art installation memorializing a tram stop, which became a tram stop.

Inside this metro station is a section of the city's former medieval fortification.

Rotterdammers' dirty minds gave this Santa a dirty nickname and cursed it to a life of wandering.

This bronze statue was dedicated to a 1966 Beatles hit.

Though it's not the largest, this one-kilometer outdoor market is reportedly the longest in Europe.

Taking the subway here means doing so over a bridge located in the middle of an estuary.

A section of the long chain that blocked enemy ships from entering Constantinople.

This half-forgotten fortress was constructed by the Ottoman conqueror of Constantinople.

This former Imperial summer home was the venue for a royal slap that once echoed 'round the world.

A gorgeous, Gaudí-esque stairway constructed in the city of Istanbul by a prominent Jewish family.

This crucial gathering spot along the "hippie trail" still displays old notes between traveling beatniks and backpackers.

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

A fountain standing as a testament to a doomed alliance.

1513 Turkish world map, full of European state secrets and snarky commentary.

This column celebrates Rome's victory over the Goths, and may be the oldest Roman monument in Istanbul.

No one is sure if the world's fourth-largest diamond had been found in a rubbish heap or was pawned by Napoleon's mom.

This remarkably well-preserved Egyptian plinth is pretty well traveled for a giant piece of stone.

The largest stone circle in Ireland.

Launched by Napoleon's soldiers more than 200 years ago, a cannonball remains embedded in the tower wall.

This building has two facades of clashing architectural designs.

A turn of the century building boasting some of the most beautiful art nouveau architecture in Prague.

Increasingly decayed figures stand as a powerful reminder of the human costs of Czech Communism.

What looks like a suicide in progress is actually a statue of Sigmund Freud.