Beneath the city of Lourdes, France is a massive, concrete church.

Mysterious meeting place for UFO hunters near Area 51.

Kings Cross Station pays tribute to its role in Britain's best-selling book series.

Bring your own cardboard to the slippery slopes of concrete hidden in a neighborhood park.

An abandoned saucer-shaped monument in the Bulgarian mountains.

A bunker "with enough U.S. currency to replenish the cash supply east of the Mississippi" in the event of nuclear war now protects nitrate film.

Dramatic river bend surrounds a natural red-rocked pedestal.

The remains of diamond fever taken over by the desert.

Island where motor vehicles are banned -- home to the only carless highway in the United States.

One of the largest, oldest, darkest, quietest motel rooms in the world.

A church of bones, decorated with 40,000 human skeletons.

Only museum dedicated to women pilots, with personal artifacts from Amelia Earhart and other aviatrixes.

Designed by Buckminster Fuller, this relic of the 67 Expo survived fire and ice.

The only surviving prototype of Buckminster Fuller's revolutionary car.

An archive of nearly every day of Buckminster Fuller's life.

The only surviving prototype for Buckminster Fuller's house of the future.

Small monoliths of several varieties of stone sit alongside a wooded path in the Bronx.

A museum documents the development of the invention that tamed the Wild West.

The watery grave of Captain Bligh's famous ship.

The last remaining relic of San Francisco's glittering 1915 Panama Pacific Exposition.

A WWI fighter plane and turn-of-the-century penny candy shop are among the unexpected features of this Financial District building.

Museum on French naval history, with magnificent figureheads, a historic diving suit, and a boat used by Napoleon.

A place of great reverence for Trekkies everywhere, a hero's future birthplace.

New York City's smallest piece of private property.