The one-time watch house for incoming ships at the Golden Gate now stands abandoned and hidden in trees.

Once the largest windmill outside of Holland, with enormous 114 foot sails.

A playing field for a popular French past time can be found tucked away in a quiet corner of Golden Gate Park.

The remains of a ruined mansion memorialize the 1906 earthquake.

A monumental cross hides in the trees in Golden Gate Park.

An artsy hidden staircase leads to breathtaking views of San Francisco.

Gold Rush-era tombstones line the park's paths.

San Francisco’s century-old Christmas Tree.

The best place in the park to test out your throwing arm.

The oldest lawn bowling club in the United States.

The legendary statue-hating superintendent of Golden Gate Park is honored with... a statue.

San Francisco's first World's Fair, dedicated to the wonders of California.

San Franciscans leave gifts and messages for the magical beings that live behind the tiny, mysterious door installed on a tree in Golden Gate Park.

Possible relics of the ancient Roman city are hidden in this restaurant's façade.

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

A no-frills cinephile haven known for showing offbeat, underseen films.

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

A dark patch of the ceiling at Grand Central Terminal which was not restored is still stained brown by tobacco.

The notorious headquarters of a corrupt political machine.

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

Commemorating the spot where the famous scientist fed his pigeons.

A Victorian cemetery in the heart of Brooklyn remains a popular mecca of morbid curiosity.

The fanciest public restroom in New York City boasts fresh flowers, art, and a classical music soundtrack.

This enormous Hindu temple in Queens serves incredible dosas in its basement canteen.