The last of Philadelphia's wood-paved streets is now a landmark of terrible engineering.

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

No one knows who painted this mysterious mural in a Penn State basement.

This Delaware River bridge is emblazoned with a catty slogan from a more prosperous time.

This strange, big-tailed beast became a Pennsylvania town's unofficial mascot.

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.

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

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

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

A historic covered bridge is but one example of an oddly prevalent American urban legend.

The oldest farmer's market in America is so ancient it was approved by the King of England.

The only way to see Pittsburgh is from the top of this lookout point, just like the ancient members of the native peoples did.

Yo, Adrian!

The internal railway of one of the biggest steel plants in America has been transformed into a linear park with unique industrial views.

This palatial botanical garden is home to one of the largest pipe organs ever installed in a private residence, and a piece of Wood's cycad.

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

A layered tribute to the work of mosaicist Isaiah Zagar.

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

This 1,700-pound edible sculpture is way better than your average chocolate mousse.

The world's only and thus largest collection of its kind celebrates everyday wonder through simple umbrella sheaths.

When the town wouldn't allow the fast-food behemoth to build a new restaurant, they put one inside an 1850 home.

This handsome giant is said to mark the birthplace of the mythical woodsman and even had a cameo in a Stephen King novel.

The world's largest rotating world.