A memorial to the nearly 10,000 American soldiers laid to rest on the beaches of Normandy during WWII.

The vast chamber inside this abandoned cooling tower looks like something out of a sci-fi dystopia.

This sprawling Belgian fort was once thought of as impenetrable but now it is simply an abandoned relic.

An open-air sewer system that was covered piece-by-piece over 300 years.

A Cold War command center is hidden under an idyllic countryside.

Ancient man-made caves underneath small town Belgium.

A Belgian self-built tower inspired by the Bible and ancient civilizations.

Hiding the longest subterranean river known in the world.

This ghost town in Belgium will lose its street art when it ceases to exist.

This fairytale castle was built as a show of power but was nearly torn down thanks to its history of torture.

Hidden in an Italian forest is a completely homemade amusement park that has taken a lifetime to create.

Every Christmas, one Arizona city makes the most of its dry climate by creating an arid desert tannenbaum.

A self-built castle made by a mysterious man.

Thousands of Mexican Free-Tailed Bats soar around an abandoned storm drain at sunset each summer.

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

This rustic cabin, outfitted with gun slits, was once home to John D. Tewksbury, patriarch of the bloodiest family feud in American history.