Mysterious rocks that ring musically when struck.

A toxic ghost town sitting atop a massive coal fire.

A grand New York post office that is home to mailman Santas, scraps of postal history, and a pneumatic mail system.

Tucked in the back of this amazing antique store is an important piece of medical history.

The greatest real estate coup of all time.

Commemorating the spot where the famous scientist fed his pigeons.

Avoid gangster interaction while window-shopping.

Cryptic messages embedded in the New York City sidewalk.

Try not to get slimed in Tribeca.

Dodge prohibitionists and slide through the telephone booth in Crif Dogs.

A terrific purveyor of natural history objects and curios.

This beloved marketplace mascot poops money and grants good luck.

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

An Irish Memorial commemorating those who perished due to potato blight.

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

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.

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.

Philadelphia boasts one of the best — and most often overlooked — traditional Japanese gardens in North America.

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.

The world’s first penitentiary, meant to be humane, drove men insane.

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