In all of the 29 years it was in operation, no prisoners ever escaped successfully... or so they claim.

Stockholm's decidedly unique public transit system has doubled as the world's longest art gallery for decades.

Old Danish castle immortalized in Shakespeare's Hamlet.

Danish tourist destination well known for open stalls where vendors sell marijuana on the street.

The gorgeous entrances into the city's underbelly look more like grand halls than subway stops.

Thirteen sculptures in central Moscow graphically depicting vices of the modern world.

Dozens of padlock-trees along the Moscow River.

A sculpture park of the tossed aside relics of the USSR, from Stalin to a massive Soviet emblem.

One of the world's tallest statues is also one of its most hated.

A replica of the steam engine that hauled Queen Victoria's Royal Train is on display at Windsor.

This stunning blue and gold room changed cities twice before becoming part of the Smithsonian.

The Tudor-style cottage in the middle of the square is not quite what it seems.

This colonial tavern played host to George Washington, Thomas Jefferson, and other famous early Americans.

A blend of art, antiquities, and Americana fill this museum, surrounded by whimsical, enchanting gardens.

A hidden passageway now marks the site of an assassination attempt on Ronald Reagan that some say broke a 140-year-old curse.

The oldest building in the District of Columbia was preserved because of a mistaken connection to George Washington.

The now-overgrown beach resort was once frequented by Yugoslav military elite.

A little marble compass above George Washington's (empty) tomb in the Capitol marks where D.C.'s four quadrants intersect.

Was there a small "backpack nuke" hidden in the attic? JFK apparently thought so.

Twelve grave-faced marble angels guard the emperor's tomb at Les Invalides.

Behind an abandoned storefront is an example of pioneering 1930s gas station architecture.

This historic covered bridge contains a series of macabre paintings that communicate one thing: everyone dies.

This poor little statue is the most vandalized memorial in Washington.

This unacceptably tall building was the real reason for Washington, D.C.'s skyscraper ban.