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

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

The 28-foot granite map plots the locations of 40 theaters in New York City.

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

This wall on a street corner in Lower Manhattan has been a blank canvas for a rotation of renowned artists since the 1980s.

New York City's only radical feminist independent bookstore.

Salute the leader of the proletariat.

Phil Mortillaro uses keys to bring art back to the Village.

Avoid gangster interaction while window-shopping.

There must be a pun in this haystack somewhere...

Try not to get slimed in Tribeca.

An artist's cute bronze subway sculptures belie his violent artistic past.

An uber-secure, windowless tower of doom in the center of Manhattan is an NSA spyscraper.

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

The New York hotel where tragic visionary Nikola Tesla spent his final hours, destitute and alone but for the pigeons.

This historic address is home to the beloved ball and is an almost totally empty building among the most expensive real estate in the world.

The facade of this 16th-century building is decorated with carvings of 300 seashells.

These magnificent city walls rise from the barren sun-baked Spanish plains like something straight out of a fairytale.

This magnificent castle grew from a small Moorish fortress, and reportedly inspired two iconic Disney castles.

This underground church is topped with a 500-foot cross that is seen by many as a beacon of fascist hubris.

According to tradition, King Phillip II supervised construction of the seat of his empire from this seat carved into rock.

The mysterious large white cross visible from the runway is a memorial to a massacre during Spanish Civil War.

A pair of gigantic baby heads greet passengers at Atocha Station.

A lush indoor jungle fills this bustling Madrid transportation hub.