The only geyser in the state of Pennsylvania is caused by pressure from an abandoned coal mine outside of the ghost town Centralia.

A toxic ghost town sitting atop a massive coal fire.

A trading post in the North Pole where children send letters.

Built by the patriotic residents of Boonsboro in a single day.

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

Whisper secrets in a busy station only to be heard on the other side of this acoustic arch.

Now famous as the "Harry Potter bridge," this impressive concrete viaduct has long been an icon in its own right.

The most iconic structure in Scotland has been home to bishops, colonels, and Sean Connery characters.

A sweet symbol marks the place where torturous executions were once carried out.

Overlooked by many, the two famous Scottish warriors guard the main gate of Edinburgh Castle.

A blend of art, antiquities, and Americana fill this museum, surrounded by whimsical, enchanting gardens.

The Dover International Speedway is home to a towering, concrete-skinned, racecar-hungry behemoth.

This collection of odd proofs of concept is like taking a walk through the imagination of a Victorian engineer.

An homage to Jackie Gleason's bus-driving character from 'The Honeymooners.'

This 25-foot-tall gorilla made his way from the Wildwood boardwalk to a Pine Barrens gas station and deli.

In the power of this waterfall, Alexander Hamilton saw the potential for industry.

Infamous marsh filled with toxic waste, World War II-era London rubble, and dead mobsters galore.

Memorial built in 1922 in remembrance of WWI casualties.

World Trade Center memorial likened to a woman's sexual organ.

The highest point in New Jersey is marked by a massive, if simply named, obelisk.

Hundreds of glow-in-the-dark objects light up a museum in a historic zinc mine.

A giant time capsule not scheduled to be cored until 2040.

The seat of the lost Ryukyu Kingdom has survived numerous fires and wars over the centuries.

It has an American Dream Car exhibit, Europe's largest Formula One collection, and many, many mannequins.