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

Home to the largest urban bat colony in North America, estimated at 1.5 million bats.

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

An uber-secure, windowless tower of doom in the center of Manhattan is an NSA spyscraper.

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

The iconic Manhattan corner that was once the site of the Beastie Boys' fake clothing store.

A quiet and contemplative oasis in the middle of New York's bustle and riot.

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

Hidden inside this Arizona fast food franchise is an in-depth exhibit on the famed WWII counterintelligence program.

Love, knishes, and best wishes from this legendary Lower East Side bakery.

This abandoned factory on the Hudson River once churned out a million bricks a week.

This abstract sculpture is rumored to cast a hammer-and-sickle shadow once a year.

Gaudí's famously flamboyant architectural style is on full display in this sprawling park and garden.

A 19th-century Baja cantina that many say is the birthplace of the margarita.

The perfectly preserved underground rooms where Churchill plotted the war against Germany.

This monument to a veteran of the Mexican-American War is one of only two in Manhattan that serve as an actual mausoleum.

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

A 19th-century politician who died after walking home in a blizzard is honored with this Manhattan statue.

One of the few remaining American elm trees in New York’s Tompkins Square Park was the birthplace of a new religion.

The last of its kind in the country.

Berthed at the Charlestown Navy Yard in Boston, "Old Ironsides" is the oldest commissioned warship still afloat.

In its day this historic fort held 100 cannons pointed in almost every direction to protect New York.

One man's exploration of the human form, including the bizarre and delightful "Man Attacked by Babies."

Home to three historic ships from the age of Vikings.