This Boston medical museum features the skull of the famous medical case of Phineas Gage.

This collection of grinning ephemera has grown from basement to Brooklyn.

The beautiful tunnel that ran from the lobby to Penn Station is still hidden underneath 34th Street.

The saddest little diner in New York.

Make a tough dinner decision: Octopus wasabi roulette or bull penis?

This abandoned subway station can still be seen on regular commuter trips.

Deep under Manhattan is the largest construction project in city history. So far, the project has taken the lives of 23 workers, or "a man a mile."

Become a prohibition rebel.

Order scoops of pandan, lychee, and black sesame at this family-run institution.

This abandoned subway station beneath the Waldorf-Astoria hotel is allegedly used to secretly transport presidents.

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

A crumbling hospital from the 1850s on Roosevelt Island.

A tiny museum housed in a New York freight elevator specializes in the "overlooked, dismissed, or ignored."

The haunting, dilapidated remains of a former poorhouse on Staten Island's Greenbelt.

This wall on a street corner in Lower Manhattan has been a blank canvas for a rotation of renowned artists since the 1980s.

This Pringle-shaped ledge makes for the perfect photo op.

San Franciscans leave gifts and messages for the magical beings that live behind the tiny, mysterious door installed on a tree in Golden Gate Park.

These beautiful ruins deep in the Pennsylvania woods are thought to have been a ski lodge or a speakeasy, but no one really knows.

This tiny, charming synagogue in the Cayman Islands was built by a man as a present for his Jewish wife.

Abandoned railway line circling the city of Paris.

This quirky curiosity shop takes its cues from the world's bazaars.

The vast, legendary catacombs hold secrets much stranger than stacked bones.

The curious underground history of keeping Paris clean.

A museum dedicated to the strange and extravagant costumes and memorabilia of the mummers, a tradition older than Philadelphia itself.