A phenomenal assembly of pueblos in New Mexico is the most complete example of ancient ruins north of the border.

These decaying bridges 1,000 feet high are a reminder of the skill it took to cross the Colorado Rockies by rail.

A sign marks the plane crash that caused two nuclear bombs to fall in North Carolina.

A six-foot pair of socks hangs from a drawer of the world's largest bureau.

This bright yellow relic is the final survivor of a short burst of seashell-shaped petrol pumps.

A cabin completely covered in coffee mugs, where visitors are welcome to leave one of their own—if they can find an empty nail.

Live long and prosper in Tennessee.

The secret city built by the Manhattan Project.

The remains of the iconic train crash from the movie The Fugitive can still be found rusting along the Great Smoky Railroad.

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

The largest earthwork effigy in the world.

Nine of the very few concrete ships ever made in the U.S. are beautifully decaying off a Virginia pier.

This road in the Great Smoky Mountains was supposed to assuage a displaced community, but ended up a $52 million dead end.

A 300-yard long natural tunnel runs through a ridge deep in the Appalachian Mountains.