The remains of a Canadian train crash are now mouldering beneath layers of rust and graffiti.

This Upper East Side apartment co-op was designed as a tuberculosis sanitarium.

The only remaining building in New York to see the inauguration of a president is being slowly overtaken by a grocery store.

A well-worn marker in a forgotten alleyway is all that remains of what had been one of Manhattan's most beautiful buildings.

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."

Manhattan's deadly West Side railroad, which killed hundreds of New Yorkers, is remembered by this simple plaque.

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

This was one of the first (and last) university-built and operated nuclear reactors.

Built hundreds of years ago this downtown iron barrier once protected a much despised king.

An odd, ancient window that may have once been part of a brutal prison is embedded in the side of New York's Police Plaza.

Unrepaired walls from a 1920 anarchist bomb attack.

The only home that Alexander Hamilton ever owned has a history almost as troubled as his own.

This Wall Street bar was once a hub of revolutionary activity where Washington famously bid farewell to his troops.

The oldest house in Manhattan is now a museum that remembers the home's sordid history of scandals, vice-presidents, and ghosts.

Walk over a 150 year old manhole.

Hidden in Central Park's Ramble is a troublesome cave buried just beneath the surface.

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

One of only two commuter aerial tramways in the United States.

New York City's smallest piece of private property.

A tiny monument to the unsuccessful attempt by Thomas Jefferson to place the prime meridian in Washington.

This innocent-looking townhome is actually a subway exit.

Wall Street has a new heroine, a bronze statue of a small but fierce girl.

More gold than anywhere else, ever.

This beautiful building in the heart of Manhattan's Financial District was empty for decades.