Amid skyscrapers and traffic exists this unique aquatic ecosystem.

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

One of the few remaining American elm trees in New York’s Tompkins Square Park was the birthplace of a new religion.

What happens here stays here – unless it affects the whole world.

A bit of retro transportation flair preserved in the world's largest department store.

The "Seinfeld" diner.

From this desk Al Hirschfeld drew his influential caricatures of the 20th century's Broadway stars.

The best place in New York to pick up the controversial, notoriously foul-smelling Asian "king of fruits."

Under a glass sidewalk lie the remains of some of Manhattan's oldest buildings.

The fanciest public restroom in New York City boasts fresh flowers, art, and a classical music soundtrack.

The last living thing to come out of the rubble after 9/11 is now a symbol of hope and resilience.

The first piece of public art dedicated to LGBT rights.

Historical figures from New York City's Catholic community reside in Midtown.

This slender three-story building has also had several famous residents.

A Ukrainian church canteen doles out hearty fare in an East Village basement.

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

Collection of skeletal systems from the "world's leading supplier of osteological specimens."

An immersive art experience built by local arts collaborative, Factory Obscura, in the building formerly known as The Womb, a psychedelic arts center founded by the frontman of the Flaming Lips.

An old spiral fire escape dangles above a public courtyard in Midtown Oklahoma City.

Trick water gardens from 1619 featuring a 200 piece mechanical theater powered by water.

This classic restaurant features a gorgeous mirror-clad room.

Art installations, derelict railcars, and endangered grasshoppers all call this south Berlin park home.

The original burial place of this preeminent 18th-century Jewish philosopher was razed by the Nazis.

At one of Berlin’s oldest churches, visitors can place mosaic tiles to help restore a medieval mural.