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

What looks like a simple quaint estate in rural Pennsylvania was in the 18th century home to a small monastic community.

One of the oldest of its kind.

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

Steepest flood safety railway in the entire world.

A tour de force of a fountain, memorializing a man who loved fountains more than anything else.

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

One of the oldest log cabins in America is one of the last of its kind this historic Swedish dwelling remains a piece of living history.

A tradition unlike any other, this marks the site of the annual Groundhog's Day tradition.

One of the U.S. Forest Service's only mansions is outfitted with a dinner table for floating food.

North America's oldest quarantine facility was built in response to Philadelphia's 1793 yellow fever outbreak.

Locals call this magical moss-covered walkway the "Emerald Path."

Long hidden under grime, the politically radical murals of a little known Yugoslavian master are finally getting their due.

A field of nothing but boulders which resembles a giant's gravel driveway.

Current docking place of the SS United States, the fastest transatlantic ocean liner.

Erected in 1697 this Philadelphia bridge is the oldest surviving roadway bridge and perhaps the oldest stone bridge in the United States.

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

This stone tower marks a lookout point over the historic Washington Crossing, and maybe some buried treasure.

Behold the rickety wooden glory of the world's oldest operating roller coaster.

This jail which was in service for over a century is now open for curious visitors.

Once on display alongside a giant Gumby, it’s as tall as a nine-story building when fully extended.

This huge, disused viaduct is now a crumbling concrete underworld of covered in years of graffiti.

A local prank turned town icon.

This Pennsylvania cave holds evidence of the oldest known inhabitants of North America.