Once one of the world's great cities, Cahokia was a place of religious worship, trade and mass human sacrifice before being mysteriously abandoned.

Built following the War of 1812, this fort has withstood hurricanes for centuries.

The now-serene site of the largest earthquake ever recorded in North America.

Running under an entire mountain, the longest highway tunnel in North America is kept fresh using portal fans and jet fans.

This small city where almost everyone lives in the same building can only be reached via North America's longest tunnel.

A colorful, century-old cemetery of the Yaqui Indian Tribe hidden amid the suburban sprawl of Tempe, Arizona.

Once a year, at exactly 11:11 a.m., this monument comes to life.

Come for the pizza, stay for a performance on the world's largest theater pipe organ.

Walk through the actual strap iron cells and solitary chambers of Arizona Territory’s first prison.

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

This monumental Jesus is often referred to as "Our Milk Carton With Arms."

A beautiful footbridge with over 2,000 glass sculptures along the walls and ceiling.

The highest point in Washington state is a volcano covered in glaciers.

The remains of this visionary community can still be found much as it was a century ago.

A statue honoring 44 continuous years of greeting passing ships.

Mass graves and Victorian monuments mark the history of Memphis in this 19th century cemetery.

Elvis's own personal tropical hideaway.

Rusted and decayed, this former mining site is a portal to the past.

A historic, scenic mill that was forced to close due to overlogging.

This museum features the original car used on the Beverly Hillbillies sitcom.

Often referred to as the largest spring in America.

One of the deepest springs in Missouri.

When he found his hometown was no more, Lowell Davis decided to recreate a "new" ghost town from scratch.

Where the author wrote her beloved "Little House" books.