This monument to a veteran of the Mexican-American War is one of only two in Manhattan that serve as an actual mausoleum.

Twenty-three trees, each paired with a basalt stone, line a street in Chelsea, continuing an urban project started by German Fluxus artist Joseph Beuys.

Nope, not Washington Irving's house.

This simple Manhattan salt house is artfully shaped... well, like a giant granule of salt.

On this island, you suck away your garbage via an elaborate pneumatic tube system.

A forgotten relic from New York's bygone trolley system hides in plain sight under a bridge.

These ornate manhole covers were used for a now-forgotten purpose.

Magnificent New Deal Murals evoke a time when New York City harbor was one of the world's greatest and busiest ports.

The former sign of this immortal music venue is just that--undying.

This nearly invisible wire transforms much of the city into one big, symbolic home on the holy day.

A plaque immortalizes the spot where the early American spy said his famous last words: "I only regret that I have but one life to lose for my country."

The competition: breathe deeply as long as you can.

Currently housing a corporate bank branch this building at the southern tip of Manhattan was once the gateway to luxury vacationing.

Manhattan and the Bronx have been playing tug-of-war over this former island neighborhood for more than a century.

New York's unstoppable progress turned this cemetery into the smallest burial ground in the city.

Surrounded by low rise buildings and partially converted into an auto body shop, this marble archway is the only vestige of a forgotten Manhattan estate.

Monument to a forgotten NYC disaster that claimed the lives of 1,000.

A reminder to choose water over wine since 1888.

This translucent sculpture represents a quintessential component of New York City's skyline.

The home of the first American-born saint is one of the only curved buildings in New York.

Manhattan's Thirteenth Avenue was made on landfill then deliberately destroyed — apart from one small, obscure block.

This former crime corner has been turned into an eclectic community center.

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

This anonymous businessman sculpted in bronze became an enduring memorial after 9/11, and had been mistaken by rescue workers for a survivor in the rubble.