This former maximum-security prison is creepy, sobering, and supposedly haunted.

Hidden behind Lincoln's head is a 70-foot-long chamber containing enamel plates documenting American history, sealed in a teakwood box in a titanium vault.

The world's largest mountain carving could fit all of Mount Rushmore inside it many times over.

One street divides a single town that stands in two U.S. states.

All that's left of the quintessential "cabin in the woods."

Over 200 people were buried here with only a small stone to mark their final resting place.

The highest point in Florida is still the lowest high point in the country.

Site of the 1879 Cheyenne Outbreak and the site where famed Sioux chief Crazy Horse met his fate.

One of the longest water bridges in the world was built over a supposedly haunted swamp in Louisiana.

The world-record holder for the longest bridge stretching continuously over water.

The fifth-longest suspension bridge the world, connecting one Michigan peninsula to another.

Giant novelty guitars now mark the spot where Robert Johnson is said to have sold his soul to the devil.

This hotel was used during the Manhattan Project to house official visitors.

The secret city built by the Manhattan Project.

All you ever needed or wanted to know about America's favorite whiskey, but not a drop to drink.

This boulder stays on its mountain thanks to a huge chain and on the map due to local legend.

Kentucky, Tennessee, and Virginia meet at this point in the Cumberland Gap.

A historic dam made famous for its turbines and feature in a Hollywood classic.

The world's largest set of the ten commandments lay nestled in the heart of the Great Smoky Mountains.

This winding road of 318 curves is a must-visit for (careful) motorcycle and sports car enthusiasts.

The highest point in Tennessee, Clingmans Dome bears witness to the ravages of one type of insect.

One man has spent decades faithfully constructing this unique brick and cinderblock castle.

While knives are the main feature in this store, visitors will also find dinosaur bones and meteorites.

This 19th-century building inadvertently preserved the handprints of its builders within its walls.