World's largest college campus includes a wildlife sanctuary and a former movie set on more than 28,000 acres.

One person's lost luggage is another person's treasure.

Oldest existing wire suspension bridge in the United States.

An abandoned castle owned and ignored by Masons carries a cursed history.

Enormous lake at the bottom of a unique cave system.

The world's longest known cave system.

Labor provided by Great Depression-era programs restored these 25,000 acres in Tennessee.

This structure among the trees was the result of divine inspiration.

This award-winning men's bathroom was just too beautiful to not allow women to see.

The first full-scale tunnel built in America is short but scenic.

At Chicago's revered Field Museum, visitors are invited to learn about and literally explore DNA.

This whimsical Oz-themed park had a wonderful impact on the surrounding neighborhood.

A Bibliophile's Dream.

Four glass boxes hover over 1,000 feet in the air to give visitors an unparalleled view of Chicago.

The largest self-built castle in the U.S., six decades in the making.

The real life Hobbiton, this sheep farm has been forever transformed since being built for The Hobbit film series.

A three-story copper skybridge connects two Manhattan buildings with Art Deco luxury.

Possibly the world's largest hourglass only needs to be reset every New Year's Eve.

Stunning wetlands ablaze with pink lotus flowers.

The largest tidal whirlpool in the Western Hemisphere.

This massive solar system model is sprawled out across Maine's suburban wilderness.

This scale model of our solar system hid in plain sight for years before a physics team sought out all the planets.

Mysteriously stacked storefront paths give this medieval British town an iconic style like none other.

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