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.

The largest university building in the West is a gothic masterpiece containing dozens of theme rooms based on different countries.

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

The United States’s oldest funicular railway glides up and down a steep Pittsburgh street.

Sail through this subterranean show cave that is home to a legend that would go on to name nearly everything around it.

This prehistoric sinkhole lured exclusively male mammoths to their death, much to the delight of science.

The world's largest mountain carving could fit all of Mount Rushmore inside it many times over.

This little-known Revolutionary War fort is supposedly haunted by the ghosts of its past.

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

Golden and naked, the figure that was once the highest point in New York is all that remains of the second Madison Square Garden.

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.

The body of St. John Neumann and his collection of hundreds of relics, on display in a Philly church.

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

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

Yo, Adrian!

The oldest surviving botanic garden in the United States.

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

This Philly cemetery is the eternal home of many famous area residents, including Rocky Balboa's wife.

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

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

A rare view of a preserved Victorian science museum.

An abandoned cemetery lies in ruins as the surrounding forest swallows it whole.

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