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

Built by the patriotic residents of Boonsboro in a single day.

The longest escalator in the Western Hemisphere takes over three minutes to ride down.

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

A grotesque Fiji merman dwells within this traditional Dutch-style building.

WWII-era bunkers are hidden under the beaches of this picturesque park, which is still scattered with wartime watchtowers. .

The historic home still shows the scars from a little run-in with the British in 1813.

This monument marks the beginning journey of a wounded soldier's leg that ended up almost two states away.

Home of the only civilian casualty at the Battle of Gettysburg.

Where the famed frontiersman was born, raised, and survived Quaker intrigue

The beloved, war-tested mascot of a Union regiment graces their battlefield monument.

An eccentric priest's tribute to George Washington, this chapel tells the story of the American Revolution.

This stately 19th century library pushed architectural boundaries at a time when the public library movement was just taking off.

This extraordinary Depression-era expenditure was modeled after a postcard of a Mediterranean hotel.

An Olympic hero stripped of his medals is buried in a town he never visited, which took his name after his death.

Memorializing an American tragedy of massive proportions.

A diorama of the Civil War, fought by cats.

The home of possibly the least-loved U.S. president stands as a sort of unpopular Monticello.

A small museum along the Susquehanna River is home to a rich collection of Native American artifacts.

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

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

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

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

Steepest flood safety railway in the entire world.