WWII-era bunkers are hidden under the beaches of this picturesque park, which is still scattered with wartime watchtowers. .

A scenic fort on the harbor protected Philadelphia from an attack that never came.

A desiccated merman and a walrus penis bone are among the oddities in this eclectic collection of shipwreck treasures.

This collection of odd proofs of concept is like taking a walk through the imagination of a Victorian engineer.

A blend of art, antiquities, and Americana fill this museum, surrounded by whimsical, enchanting gardens.

A wrecked ship dating back to the American Revolution was only recently discovered off the Delaware coast.

Enchanting gardens surround a derelict mansion, all hidden in plain sight behind a stone wall.

Century-old shop, specializing in Occult products.

A curious building honoring past and current members of a historic musical comedy troupe.

South Philadelphia is home to Keith Haring's only surviving in situ collaborative public mural.

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

This museum boasts a bucket of teeth and tells the tale of a 20th-century dental circus.

Instruments, apparatus, and rare books all relating to chemistry and its related sciences.

The abandoned coal loading dock is a canvas for unsanctioned art.

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

This meticulously extracted nervous system allegedly came from a 19th-century custodian who donated her body to science.

The origin of this mechanical boy was a mystery until he revealed his maker by writing it in perfect cursive.

One artist's love letter to his city and its citizens plays out across dozens of bright murals painted on the sides of decrepit buildings.

A rare view of a preserved Victorian science museum.

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

A layered tribute to the work of mosaicist Isaiah Zagar.

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.

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