A railroad magnate's replica village has become home to a genetic seed bank for rare breeds of livestock.

Abandoned Coast Artillery fort now serves as graffiti canvas and sightseeing vantage point.

Eco-friendly island mansion.

The second oldest Jewish graveyard in the U.S. is tiny, with connections to George Washington and Henry Wadsworth Longfellow.

Oldest synagogue in the United States.

A 60-room castle constructed by a horse-racing heir.

This lighthouse was witness to the end of WWII hostilities and now collects creepy cairns.

Mysterious stone tower featured in many alternative histories of the New World.

This Rhode Island mansion was a stand-in for the exteriors of Collinwood in the original "Dark Shadows" series.

Three and a half miles of cliffs, rocky beaches, Gilded Age mansions and 40 Steps to nowhere in particular.

The first American department store, and home to the largest operating musical instrument in the world.

One artist's love letter to his city and its citizens plays out across dozens of bright murals painted on the sides of decrepit buildings.

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

A daily replay of the experiment that proved the rotation of the Earth.

The sounds of the world's largest fully functioning pipe organ dazzle shoppers at a Philadelphia Macy's.

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

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

Ant sculptures march up the side of what used to be an iconic spot in punk rock lore.

Yo, Adrian!

A museum dedicated to the strange and extravagant costumes and memorabilia of the mummers, a tradition older than Philadelphia itself.

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

Tour the dark and beloved poet's former cobwebbed basement, which may have inspired "The Black Cat."

A layered tribute to the work of mosaicist Isaiah Zagar.

World's first "penitentiary," meant to be humane, drove men insane.