Blockhouse No. 1, colloquially known as The Blockhouse, is a small fort in the northern part of Central Park, in Manhattan, New York City, and is the second oldest structure in the park, aside from Cleopatra's Needle. It is located on an overlook of Manhattan schist, with a clear view of the flat surrounding areas north of Central Park. Finished in 1814, the fort was part of a series of fortifications in northern Manhattan, which originally also included three fortifications in Harlem Heights (now known as Morningside Heights). The fort is the last remaining fortification from these defenses. Frederick Law Olmsted and Calvert Vaux, the designers of Central Park, treated Blockhouse No. 1 as a picturesque ruin, romantically overrun with vines and Alpine shrubbery.