The show pony of cave systems, Fantastic Caverns manages to live up to its name.

This striking art museum holds an amazing series of curiosity cabinets.

A rotating cast of guys and dolls in front of a Washington, D.C. building.

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

The arboretum whose marshy soil sucked up the dreams of housing developers.

400 million-year old limestone caverns nestled in the Ozarks served as shelter and a hideout for cultures throughout North American history.

The celebrated eyesore created by starry-eyed sweethearts.

10,000 flowered plants bloom in the City of Roses.

The twin towers in this Chicago fountain use 50 foot tall video screens to spit on people.

The largest source of fossilized insects anywhere.

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

This $3 million model train takes you through Chicago, Seattle, and the thousands of miles in between.

This cave holds a surprisingly colorful variety of geological oddities.

This super steep hike ascends 2,000 feet in less than a mile.

This historic hotel invented the chocolate brownie.

Robots, lasers, and whoopee cushions, oh my!

The marker offers a rare chance to be in four U.S. states at once, though there's some controversy over its geographic accuracy.

The L.A. Zoo has a secret garden of rare bootleg cycads, a palm specimen dating back 280 million years.

The last moments of the ill-fated Pompeiians, frozen forever in plaster.

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

These Great Lakes sea caves accessible by boat in the summer turn into temples of ice reachable by foot in the winter.

Thanks to a quirk of elevation this gift shop produces magic doughnuts that are found nowhere else on Earth.

The only "Egyptian" pyramid in Europe and the legendary tomb of Remus.

The last of its kind in the country.