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

A portion of the old Pirates stadium over which a defining home run once flew still stands even after the rest of the stadium was torn down.

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

An almost life-sized elephant named Ms. Ellie greets visitors at this jumbo-themed museum.

Pennsylvania's highest point is spotted with boulders which were pushed to the surface by nothing but cold.

A local prank turned town icon.

This elaborate towering structure was once famed for its revolutionary height.

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

This charming colonial alleyway is one of the oldest continuously used residential streets in the U.S.

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

Frank Lloyd Wright’s most iconic home dangles over a Pennsylvania waterfall.

An abandoned stretch of highway, deteriorating next to the operational one.

The Cold War-era "underground Pentagon" is a sprawling subterranean hideaway for the Defense Department.

A diorama of the Civil War, fought by cats.

A dramatic, 360-degree recreation of Pickett's Charge in the Civil War.

This recreation of a 19th-century dime museum is full of oddities.

This rare triple-jurisdiction drawbridge passes through Virginia, Maryland, and Washington, D.C.

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

This beautiful stone arch bridge wasn't even expected to stand for one day, but people have been crossing it for centuries.

This one-room cabin where the young colonel slept during the French and Indian War.

A star fort along the C&O Canal in western Maryland that protected America in three wars.

Rediscovered after a century, the father of the American Navy was reinterred in something dredged up from Davy Jones’ locker.

This fort down the Potomac from Washington, D.C. was once the only defensive fort protecting the capital.

The final resting place of the tragic king and queen of the Jazz Age is tucked away in a small Maryland graveyard.