The "World's Largest Underground Business Complex," a 55,000,000-square-foot city underneath Missouri.

Community bookshelf of 25-foot-tall book spines.

The home made famous by the 1983 holiday classic is now a perfectly preserved shrine to the movie.

The angel of death appears to weep black tears at this grave marker.

Roses and other fascinating flora fill this garden built to commemorate Britain's immortal Bard.

Fresh wooden posts have been added to ancient holes to recreate a primitive henge clock.

To find the "unicorns of the deep" you've got to go downstairs.

A replica viking ship from the Chicago World's Fair is still in dry dock in an Illinois park.

Once one of the world's great cities, Cahokia was a place of religious worship, trade and mass human sacrifice before being mysteriously abandoned.

The only Bahá'í house of worship in North America and one of only a handful worldwide.

One of the largest aviation events in the world brings half a million aircraft enthusiasts to Wisconsin each year.

A unique botanical garden housed in three giant geodesic domes.

The Bong-area park police have asked visitors to please, stop stealing the signs.

The only Frank Lloyd Wright-designed structure in the architect's hometown.

A bronze plaque marks the site of the only show the "King of the Soul Singers" ever missed.

The remains of a enormous earthen figure of unknown origins cuts across a rural Wisconsin road.

One of Frank Lloyd Wright's final works was this UFO church.

A metal ring in the middle of the road marks the exact spot where the Soviet satellite crash-landed in 1962.

Restaurant in Northern Wisconsin comes with a unique feature: a grassy roof covered in living goats.

Hidden away in the city of Madison, Wisconsin is a nearly forgotten home that Frank Lloyd Wright built for a childhood friend.

This cave holds a surprisingly colorful variety of geological oddities.

A favorite Paris bar for U.S. expats, including Gershwin, Hemingway, and James Bond.

High atop the Eiffel Tower is a small apartment built exclusively to entertain the science elite and make the rest of Paris jealous.

France's most famous cemetery, with some of its most curious tombs.