Rebuilt remains of a temple to Roman god Mithras.

This landmark church concealed a crypt packed with bones that was discovered thanks to the London Blitz.

The largest of London's subterranean rivers and once a mad, bad center of London life.

The remains of the great moral philosopher reside in a university in London.

This London plaque marks the spot where David Bowie's famous alien made his debut.

Bronze sculpture celebrating the relationship between Churchill and Roosevelt.

The popularity of Sherlock Holmes led to the creation of his fictional address, turning the orderly London street numbers askew.

An all-American grocery store in Paris sells U.S. "cuisine" like Pop-Tarts and Heinz ketchup to homesick ex-pats.

A lone cannonball remains lodged in the walls of the Hotel de Sens as a sober reminder of a revolution.

The very center of Paris is surrounded by a bevy of strange good luck rituals.

This innocuous-seeming building is actually the remnant of a major wartime brothel.

The water-powered carriages are long gone, but for over a century this funicular railway has been the fastest route to the highest point in Paris.

The celebrated eyesore created by starry-eyed sweethearts.

This former “ante-chamber to the guillotine” has been refurbished to illustrate the brutal history of French justice.

A series of abstract, silly sculptures represent the works of a great modern classical composer.

An "inside out" building in the historical center of Paris, featuring Europe’s largest modern art museum.

Dolls of all shapes and sizes display the eras of femininity in this spooky and beautiful collection.

"In the Dark" Restaurant in Paris offers dinner in complete darkness.

A mechanized clock where a man fights off a dragon, crab, and rooster.

Beggars were miraculously "cured" of their fake ailments when they returned home to this 17th century Paris slum each night.

An enormous, 30-story-deep hole in the middle of Guatemala City.

Remote Honduran Islands with a colorful history.

A massive underwater sinkhole made famous by Jacques Cousteau.

These colorful sawdust illustrations are trampled into non-existence only moments after they are finished.