Two New York rooftops are home to the largest rooftop soil farms in the world.

Five varieties of trees with custom-designed grates around the trunk are planted along the route of the Seattle Transit Tunnel.

This otherwise innocuous bodega was once the headquarters of the most feared assassin's guild in American history.

Residents of this Brooklyn neighborhood may be unaware their houses sit atop a buried trolley graveyard.

This preserved wilderness hides the remains of a colonial grain mill used to feed George Washington's troops.

Come for the pastrami, stay for the million-dollar art.

This Queens hospital has stood abandoned for almost 20 years after its patients were secretly relocated in the dead of night.

A former seaside jewel built for the everyman is now simply a neglected art deco fortress.

This abandoned seaside fortress is now simply an imposing ruin being taken back by nature.

First a horse rendering plant, then a 19th century landfill, this beach is full of glass from thousands upon thousands of broken bottles.

The home of aviation trailblazers, in a remote corner of the big city.

This elaborate tunnel is the first structure composed of cast concrete in the United States.

The neighborhood of Eagle Rock is named after a gigantic boulder with a shadowy surprise.

Nine nice parcels of land along a flight path offer a quiet respite... until a plane soars overhead.

A once crucial portion of the Long Island railroad still lays abandoned, waiting to be turned into an urban park.

Chefs from Tibet's Kham region offer steaming meat pies and noodle soups in this nook behind a jewelry store.

A remnant from the golden age of aviation still in use today, Pan Am's Clipper service took off from this Art Deco gem.

An everyday Jackson Heights bodega conceals a Mexican seafood paradise.

A young woman's senseless murder led to the controversial psychological theory of the "bystander effect."

An eerie reminder to the horrors of World War II.

A bronze plaque at an intersection in Hoboken marks the place where the game of baseball first took shape.

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

A retired subway car stands alone in a field in the middle of Queens.

A hyper-luxurious, 12,000- square foot home might be buried beneath Queens, still waiting to protect you from nuclear missiles.