The mysterious wonder of an underground waterfall is illuminated by multicolored lights.

A museum dedicated to the alleged Roswell Incident.

A monument to the art of slicing people open.

A Bibliophile's Dream.

A self-built castle made by a mysterious man.

A lush green oasis in the middle of Chicago.

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

The first declared National Monument in the United States.

Ninety feet off the valley floor is an ancient dwelling put under protection of the U.S. government by Teddy Roosevelt.

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

This massive stained-glass masterpiece is thought to be the largest Tiffany dome in existence.

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

A walk through the historic city center, under the streets of Seattle.

In all of the 29 years it was in operation, no prisoners ever escaped successfully... or so they claim.

A peculiar mansion built by the troubled heir to the Winchester Rifle Company fortune.

This iconic L.A. bookshop is housed in an abandoned bank—both symbolic and chic.