A secretive collection featuring objects that were designed specifically for U.S. intelligence operations.

The highest bridge in America was built for an almost unnervingly small amount of money.

Who needs fancy modern water slides when this giant North Carolina rock works just as well?

The longest navigable underground river in the United States is home to countless blind and albino animals.

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

A short hike into the mountainside forest reveals a decaying 1890s town.

The "Fun Spot of the Desert" is now a haunting ruin, and a reminder that putting a water park in a desert is a bad idea.

The artist James Turrell is repurposing an extinct volcano crater as an observatory to experience the cosmos.

Half of a waterfall goes into the river while the other half seems to disappear.

An organ located deep within a cave, whose "pipes" are the geological features of the cave itself.

A Saint Nicholas-themed ghost town in the Mojave desert.

A small flooded ghost town with a few scattered structures remaining.

Shop of curiosities with a dinosaur museum tucked in its basement.

A Victorian mansion, painstakingly reproduced to appear just as the the Munster's family home did on TV.

Once a mortuary that held the remains of Buffalo Bill, this Denver hotspot is now a death-fixated restaurant.

An uber-secure, windowless tower of doom in the center of Manhattan is an NSA spyscraper.

One of the largest, oldest, darkest, quietest motel rooms in the world.

This family mausoleum is steeped in symbolism and looks more like a fantasy location than a grave.

Dig for your own trilobites in this goldmine of invertebrates.

Stay in a room with a view... of the bottom of the ocean.

This "zoo" is a cross between a junkyard and a sculpture garden, featuring animals you won't see anywhere else.

These millipedes glow not out of attraction, but as a not-too-subtle warning.

This massive redwood tree has a hole in the base big enough to drive through.

The lush coastal city of Astoria is riddled with forgotten secret sidewalks.