The front yard of an Upper East Side town house hides the last fragment of one of New York's most famous theatres.

Hidden in Central Park's Ramble is a troublesome cave buried just beneath the surface.

The oldest family-run luncheonette in New York, last renovated in 1948, still serves food and drinks the old-fashioned way.

Unique antiquarian shop specializing in globes, maps, and prints.

A New York garbage depot holds a secret collection of weird and wonderful refuse.

This hidden library of physiological ephemera contains centuries worth of knowledge on the vim and viscera of the human body.

Peek through the gates at this oasis from the city, full of Old English charm.

The only home that Alexander Hamilton ever owned has a history almost as troubled as his own.

These small stands sell Malian snacks to worshippers and passersby after Friday prayers in Harlem.

The oldest house in Manhattan is now a museum that remembers the home's sordid history of scandals, vice-presidents, and ghosts.

A discreet little stairway on St. Nicholas Avenue leads to a quaint and unexpected cobblestone street of 19th century wooden rowhouses.

Six peaceful acres in a residential neighborhood dedicated to art and peace.

A winding, cliffside stretch of road overlooking the Delaware River.

The dairy farm in upstate New York where nearly half a million people gathered for three days of peace and music in 1969.

Whimsical artist house in the New Jersey woods.

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

The remains of a community that was forced to move for a dam that never materialized still rot in this Pennsylvania park.

A planned settlement in Pennsylvania once housed the aristocratic refugees of the French Revolution.

It marks the spooky spot where the bodies of two young boys were found in the 19th century.

Bizarre Cavern.

This beautiful stone arch bridge wasn't even expected to stand for one day, but people have been crossing it for centuries.

The ruined remains of a coal mining ghost town are hidden within the woods.

This schoolhouse for Black American children is one of the oldest remaining in southeastern Ohio.

This Pennsylvania cave holds evidence of the oldest known inhabitants of North America.