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

Underneath the bustling city streets, a hydroponic farm grows unique herbs in an urban oasis.

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.

These historic buildings once housed the headquarters of one of the most infamous gangs of New York.

This humble historic facade hides a history of boozing and the gentlemanly sport of rat-fighting.

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

Have a steam and some blini at this cafe in a century-old bathhouse.

A small part of lower Manhattan is actually made from a bit of England.

New York City's only radical feminist independent bookstore.

This nostalgic blast from the grooming past is also a working barbershop.

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

This study room in the New York Public Library saw the creation of one of contemporary America's greatest traitors.

Pulled from the rubble of one of the worst modern tragedies, a steel crossbeam became a symbol of hope for New Yorkers.

Those belting out show tunes might not realize this piano bar marks the site where Thomas Paine died in 1809.

The greatest real estate coup of all time.

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

Site of the first pathological and bacteriological research facility in the United States.

The former home of the reclusive "Weird Wendels" who dominated New York real estate a century before Donald Trump.

A reminder to choose water over wine since 1888.

This 220-year-old house is a reminder of New York City's Dutch past.

This castle-like building in Manhattan helped destigmatize cancer in the 19th century.

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

This speakeasy continues the Prohibition-era legacy of Harlem's jazzy Swing Street.

Once considered the height of medical modernity, this structure is now the oldest remaining component of Roosevelt Hospital.