Yo, Adrian!

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

Dr Barnes' $25 billion private collection of art and arboretum.

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

America's most famous museum of medical oddities is home to the remains of Albert Einstein's brain.

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

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

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

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.

The oldest surviving botanic garden in the United States.

Where America's first doomsday cult awaited the end of the world.

Contrary to popular belief, this secluded statue doesn't represent Pennsylvania's founder.

The highest point in Delaware is located under a trailer so this marker across the street will have to do.

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

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

The highest point in New Jersey is marked by a massive, if simply named, obelisk.

Cryptic messages embedded in the New York City sidewalk.

This historic address is home to the beloved ball and is an almost totally empty building among the most expensive real estate in the world.

Elevated freight railway turned wildly successful urban park.

Great place to have a drink and a bite to eat in an atmosphere laden with New York's Bohemian past.

Touching mementoes from those who didn't make it back from World War I still hang in one of New York's oldest bars.

A drawbridge named for a potentially intersex Polish national who fought alongside George Washington during the American Revolution, and an example of "Pulaski Red".

The remnants of two World's Fairs are here, complete with a 12-story globe, a mini-Manhattan, and a UFO-shaped pavilion.