This abandoned caretaker's apartment is one of 13 left in the New York Public Library system.

The former hotel where Tesla invented the radio.

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

Check out the underground party scene at the "Burning Man of Brooklyn."

More than 250 sakes are available in an izakaya hidden in the basement of a Midtown office building.

Wine bottle sculpture with a ship's stateroom inside.

A clock set into the concrete outside a Manhattan jeweler has been telling time underfoot for over a century.

This sculpture by artist Fritz Keonig survived the 9/11 attacks and now stands as a monument to the victims.

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

An unassuming secret door once led to a legendary watering hole.

This cemetery has graves dating back to the 17th century, including the city's oldest carved tombstone and an ominous cryptogram.

The feral felines of Roosevelt Island have a small army of allies and an abandoned hospital all to themselves.