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

For over 30 years the walls of this Harlem schoolyard have been a gallery of street art by "Kings and better."

Neon signs that grace the windows of Bergdorf Goodman's and Tiffany & Co. come from this studio in Brooklyn.

A tunnel once abandoned now thrives with graffiti art as an off-limits makeshift gallery.

Abandoned power station once home to a squatter community, now being developed into an arts center.

A living archive of urban activism and space reclaimed.

An Italian crevasse filled with abandoned buildings gives visitors a look at the world without humans.

Staircase winds down the side of Telegraph Hill through gardens, wild parrots flying overhead.

This Berlin island is home to a flock of free-roaming peacocks, as well as a historic ivory folly.

One of downtown Berlin's last reminders of its Communist past.

This jaw-dropping 19th-century bridge uses its reflection to form what appears to be a perfect circle.

This block in downtown Brooklyn was a hotbed of antislavery activism along the Underground Railroad.

Abandoned 19th century homes once occupied by naval officers, soon to be demolished.

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

The artist and New York City icon lived, worked and died in this converted carriage house owned by another iconic artist, Andy Warhol.

A popular European tradition makes its way to the states on one of America's most famous bridges.

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

La Monte Young and Marian Zazeela's "Dream House" will immerse you in an ever changing world of sound and light.

Manhattan’s Battery Park has a whimsical carousel full of spinning, glowing fish.

A partially hidden wall graffitied by spectators of the 1976 Bicentennial, recently rediscovered.

Blighted Irish field and the ruins of a 19th-century cottage on the edge of urban Manhattan.

Where now stands a 42-story condominium tower of marble, glass and steel was once the central market of New York’s slave trade.

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

The world’s oldest and biggest bookstore stocking only mystery, crime fiction, espionage, and thrillers.