This mosaic dedicated to John Lennon was tended for years by a Beatles super-fan.

Where Greenpoint's first European settler—and troublemaker—made his home.

Red frames showcase remnants of one of New York's original subway stations.

This ruined fort hidden at the top of Central Park can't seem to keep from losing its historical plaques.

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

A playground the size of a city block is a modernist monument to civic values and public housing.

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

Hiroshima survivor on Riverside Drive.

This giant boulder is sandwiched between apartment complexes in upper Manhattan.

A curious fountain that has no water and includes Satan, a crab, and 9 giraffes.

A Gothic-style abode built to accommodate the church's three resident peacocks.

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

One of the only single-person private gravesites in New York City.

Visit the monolithic tomb of America's most famous general.

Fake subway tiles were installed to cover a design that resembled the Confederate flag—it's unclear if the resemblance was intentional.

Touching mementoes from those who didn't make it back from World War I still hang in one of New York's oldest bars.

This lavish room at NYC's French Embassy is a rare relic from the end of the Gilded Age.

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

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

Curious crustaceans support an obelisk from ancient Egypt that now stands in modern-day Central Park.

The lesser-known Alice sculpture of Central Park dedicated to the “godmother of American children.”

Though its celestial ceiling is impressive, the true star is the vast collection of French books.

New York's oldest and possibly grandest keeper of books.

Rummage through this sunken ship, but leave your scuba gear at home.