A cave in southern Italy adorned with thousand-year-old Biblical frescoes existed in obscurity until fairly recently.

This palatial building houses a remarkable gallery of papal portraits.

The remains of a historic kiln once used to produce the famous Rockingham porcelain.

A cemetery that holds graves for the forgotten children of a burned orphanage.

This head-spinningly bizarre Depression-era art cave is wall-to-wall quartz and Jesus.

The final resting place of the great escape artist, where some still gather to wait for his escape from death.

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

Behind a bodega is a small museum of relics and ephemera showcasing the history of New York.

The world's oldest hologram gallery and the labyrinthine laser laboratory of a holography pioneer.

The oldest surviving synagogue in New York City is now a soaring art space.

The oldest surviving bridge in New York City, which reopened to pedestrians in 2015.

Tucked in a nondescript downtown Brooklyn mall is a bar containing a remarkable turn of the century anatomical wax collection last seen in 1920s Berlin.

Nondescript elevator doors open to reveal a stunning, surreal world.

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

This unmarked and unloved Manhattan subway grate created one of the most iconic images in American cinema.

A masterpiece of LGBT art has been restored in what may now be the most valuable restroom in America.

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

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

More gold than anywhere else, ever.

New York City's smallest piece of private property.

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

A restaurant on Staten Island showcases a different grandmother’s cooking every night.

This whimsical group of statues is a favorite of children who love to climb all over Lewis Carroll's beloved characters.

One of New York's best collections of pinball is hidden in a secret bar in the back of this laundromat.