Gang fights don't just happen on the streets, they happen under them too.

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

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.

A memorial to the first person killed by a motor vehicle in the Western Hemisphere.

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

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

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

The origins of midtown Manhattan's anachronistic wooden farmhouse remain a mystery.

The one-time epicenter of American songwriting is now a little remembered Manhattan commercial block.

The front yard of an Upper East Side town house hides the last fragment of one of New York's most famous theatres.

A collection of fanzines, recordings, and documents detailing the rise and influence of the feminist punk movement.

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

NYC's legendary underground network for bovine transportation.

A discreet little stairway on St. Nicholas Avenue leads to a quaint and unexpected cobblestone street of 19th century wooden rowhouses.

Peek through the gates at this oasis from the city, full of Old English charm.

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

Become a prohibition rebel.

The oldest surviving bridge in New York City, which reopened to pedestrians in 2015.

This strategically placed hill fort has served defensive forces from the Iron Age up until the 20th century.

Europe's largest prehistoric mound – burial site of a legendary king?

The largest stone circle in the world has ended up bringing up more questions than it has answered.

This historic building displays the remains of a victim of the devastating 14th-century plague.

These mysterious Viking chess pieces spent centuries hidden on a remote Scottish island.

Where condemned pirates met their grisly end at the gallows on the River Thames.