Couple's personal collection of pinball machines turned public pinball museum.

This double-arched masonry highway bridge is the only structure of its kind in Minnesota.

One of the only cooperatively owned bars in the nation wears its eclectic history on its walls.

The first park built over a freeway is a brutalist masterwork.

This bright yellow building is packed with sweet treats from all around the world, from chocolate-covered crickets to whoopie pies.

A striking sculpture built to honor the women of the Lakota and Dakota Nations.

One devoted couple has donated multiple recreations of Michelangelo's sculptures to this South Dakota town.

In a small Japanese garden off a busy Denver street, a memorial to a brave, principled politician.

This eclectic collection documents the wild legacies of "America's Wickedest Street."

The Denver airport is guarded by a 32-foot-tall sculpture of a demonic horse.

Golden cobblestones remember a time when this small alley was used to avoid having to give a Nazi salute.

The walls of Germany's Parliament still show the scars of the Red Army takeover in World War II.

The prototype for all Nazi concentration camps.

A fascinating insight into daily life in the Eastern Bloc.

Thousands of coffin-like pillars make up this controversial Holocaust memorial.

The fairy tale castle of the "fairy-tale king."

A tour of underground Berlin takes you through WWII air raid shelters and tunnels used to smuggle people out of East Germany.

The first permanent memorial to a unique secret weapon of World War II.

Equal parts record-breaking temple to consumerism and bizarre fun park, it's more than you think it is...

Every president in history is immortalized in bronze in downtown Rapid City.

This massive roadside mascot was the first version of the giant to illustrate his butt.

One of the world's most definitive collections of musical instruments, spanning all cultures and historical periods.

This prehistoric sinkhole lured exclusively male mammoths to their death, much to the delight of science.

The world's largest mountain carving could fit all of Mount Rushmore inside it many times over.