So many migrating birds roost on the bridge, it has a special summer speed limit.

This shifting North Carolina sand dune is an odd little desert surrounded by oceanic forest life.

The Cadillac Ranch for monster truck aficionados.

Beautiful Gothic-inspired lighthouse stands out among the run-of-the-mill striped fare on Bodies Island.

This cannonball stands as a reminder of the final act of a fleeting governor amidst a revolution.

The land is home to swimming ponies and a legendary 18th-century treasure.

The stone marker that Mason and Dixon placed at the eastern end of the famous north-south border they surveyed.

An indoor miniature village and labor of love for Laurence Geiringer, a model railroad enthusiast.

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.

Dedicated to the art and science of glass in equal measure, this space is as much laboratory as museum.

This lush forest valley was once mined for lumber to the extent that it was once nicknamed "The Pennsylvania Desert."

"Dark Sky Park" is heaven on Earth for astronomers, one of the rare U.S. locations with no artificial light pollution.

Contrary to what one might expect, ice forms inside this small cavern during the summer and melts during the winter.

Once the "Eighth Wonder of the World," this iron railroad bridge was decimated by a tornado.

The site of America's first commercial oil well essentially disappeared after the town went bust.

A quirky collection of outsider art made from automobile parts.

The oldest continually operating golf course in the United States.

The last street in Pittsburgh that's paved with wood.

There aren't too many operational funiculars around, but Pittsburgh has two!

Memorializing an American tragedy of massive proportions.

Steepest flood safety railway in the entire world.

This dramatic rail curve was once the target of a failed Nazi attack.

Rumors persist that a bottle of whiskey is sealed within this Demijohn-shaped adornment.