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.

The highest bridge in America was built for an almost unnervingly small amount of money.

European castle ruins in an American state park are actually the product of death and grief.

See massive fossils that are over 200 million years old in northeastern Arizona.

Strange red rock formations that have been attributed to a higher power for hundreds of years.

These delicate buggers are some of the rarest fossils that have bubbled up from the Tar Pits.

The largest hot spring in the United States is, as the name suggests, a stunning show of natural color.

This 4,000-foot-diameter hole is touted as "the most well known, best preserved meteorite crater on Earth."

A beautiful geyser under environmental threat.