Just your average Marie Antoinette–themed speakeasy in an abandoned 19th-century subway tunnel.

Nikola Tesla's former home contains an homage hidden from plain sight.

This ruined fort hidden at the top of Central Park can't seem to keep from losing its historical plaques.

A pedestrian island in the middle of world-famous Times Square emits a strange (and purposeful) humming noise.

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

A very classy 1920s-era bar right in Grand Central Station.

The original toys that inspired the beloved children's stories are on display at the New York Public Library.

A three-story copper skybridge connects two Manhattan buildings with Art Deco luxury.

Wall Street has a new heroine, a bronze statue of a small but fierce girl.

Great place to have a drink and a bite to eat in an atmosphere laden with New York's Bohemian past.

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

Whisper secrets in a busy station only to be heard on the other side of this acoustic arch.

A dilapidated dock tells the story of Titanic's missed arrival.

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

This lower Manhattan bar is set up in an old bank vault that rests beneath a skyscraper that hides even more historic splendor.

Try not to get slimed in Tribeca.

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

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

Amid the bustle and noise of the Financial District hides a secluded garden oasis above the city streets.

The enchanting archway is the only surviving portal into Dublin's lost medieval wall.

The 19th-century pharmacy (now a used bookstore) was featured in James Joyce’s "Ulysses," and has changed very little to this day.

This ancient Irish religious site is covered in ancient carvings, many of which have barely aged.

The world of the ancient Celtic civilization explained through a bewitching 11 acre garden.

An Irish church where an 800-year-old mummy is reaching out of his coffin as if to shake hands.