One of the largest caverns in the world has a maw large enough to stack cathedrals in.

Her final resting place was intended to be modest and private, but the power of her popularity continues to draw visitors.

It was once the base for a series of domestic terror attacks.

A collection of more than 12,000 shoes, displayed in a building shaped like a shoebox.

This legendary urban waterfall creates a dazzling display of rainbows.

A sacred site for Native Americans surveyed by George Washington and owned by both King George III and Thomas Jefferson.

A storefront museum in Asbury Park honoring the Jersey Shore’s deep history of mystery—including the Jersey Devil.

Each year, one talented artist puts on a show sculpting twelve butter-based busts of dairy princesses.

This Philly landmark has a giant butterfly pavilion, three floors of insect displays, and withstood a $40,000 heist.

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.

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

Yo, Adrian!

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

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

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

Mural made of 100,000 pieces of hand blown glass, and one of the largest glass murals in the US.

Eccentric concrete mansion and museum designed and built by hand from the inside out.

A pride of the state, this working museum crafts pottery mosaics in the style of Pennsylvania's earliest European settlers.

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

A toxic ghost town sitting atop a massive coal fire.

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

Mysterious rocks that ring musically when struck.

Hiding amid the largest camellia collection in the country lies a charming children's maze, donated by a secret admirer.