Over a thousand feet beneath the Detroit streets is a subterranean metropolis few are allowed to enter.

A group of college students hauled a desk up a mountain more than 40 years ago. The notebooks inside have become a makeshift time capsule.

This North African stone complex is considered to be the oldest astronomical observatory on Earth.

Walk down these stairs to get an underwater view of Switzerland's Lake Zug.

The ruins of a resort and casino sit on the banks of this blue hole spring that pumps 70,000 gallons of warm, clear water every minute.

From Vikings to nationwide rebellions, this castle has seen its fair share of warfare.

A puppeteer’s paradise offering shows, workshops, and an archive of over 2,000 puppets.

This bookstore serves recipes from the cookbooks on sale.

One of Scotland's most important modern structures, it just made the '100 Most Endangered Sites' list.

Albuquerque found the perfect use for tumbleweeds at Christmastime.

The American Revolution was galvanized into serious action due to the tragic clash with British soldiers that occurred at this location.

The palace window through which Protestant nobles flung two Catholic regents, thus sparking the Thirty Years' War.

This secluded village in the Andean wilderness can't be accessed by road.

This gem of Moorish architecture is slowly disintegrating along the coast of this charming town.

The romantic botanic tunnel feels like a well-kept secret.

The yawning maw of this pagan visage is said to bite off the hands of liars.

The largest airborne operation in history was launched to capture this bridge.

Organisms normally seen under a microscope decorate this church.

This historic silent film-era theater is now a community playhouse with a chilling visitor.

One of the steepest streets in the United States makes an intriguing challenge for cyclists.

Not only is this nature preserve the largest protected freshwater island on the East Coast, but it’s also a stronghold of Gullah living.

In the middle of a remote desert town is a surprisingly opulent hotel.

Richard III supposedly disposed of his nephews' bodies here in an effort to seal his claim to the throne.

One man's exploration of the human form, including the bizarre and delightful "Man Attacked by Babies."