This strange seaside tower got its name from a wealthy eccentric who would hide coins among its stones.

The largest natural travertine bridge in the world is nestled in a small canyon in central Arizona.

This Arizona observatory is famous for investigations into Martian life, and as the place humans first spotted Pluto.

Ancient pueblos built into the base of a natural canyon wall.

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

Explore the largest pure gypsum deposit in the world, and go dune sledding while you're at it.

Hollywood's most famous landmark, the "temporary" sign that has stood for decades longer than intended.

The ancient dwellings of the Puebloans, located in the cliffs of majestic mesas.

This historic address is home to the beloved ball and is an almost totally empty building among the most expensive real estate in the world.

Oldest building in California still in use.

This elaborate towering structure was once famed for its revolutionary height.

Yo, Adrian!

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

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

Some of the tallest ancient American ruins continue to inspire awe and curiosity.

The massive, incredibly rare instrument is over 11 feet tall with a range so deep it goes lower than humans can hear.

A geological mystery on Camelback Mountain.

One of the largest helium balloons in the U.S. is a 112-foot ginormous orange.