Built over a central subway station, Union Square is a bustling urban center complete with sleek megastores, upscale restaurants, fashionable bars, and a farmers Greenmarket (212/477-3220, www.cenyc.org/unionsquaregreenmarket ), operating on Monday, Wednesday, Friday, and Saturday mornings.
Laid out as a park in 1815, Union Square was originally the province of prominent local families such as the Roosevelts, who lived nearby. Then, in the mid-1800s, the city’s entertainment and commercial industries moved in. The famous Academy of Music started up on 14th Street, and department stores went up all along Broadway from 8th to 23rd Streets. This commercialism was short lived, however. By 1900 the theaters and the shops had moved uptown, to Madison Square  at 23rd Street, and Union Square was home to garment factories and immigrants.
From the 1910s until after WWII, Union Square was a center for political demonstrations. Socialists, communists, and the Wobblies (members of the Industrial Workers of the World) protested here, while many left-wing organizations had headquarters on or near the square. One of the most dramatic protests took place on August 22, 1927, the night anarchists Nicola Sacco and Bartolomeo Vanzetti were executed. The police had machine guns mounted on a roof overlooking the square, but the demonstration remained peaceful.
The 6th floor of the narrow Moorish-accented building at 33 Union Square West (between 16th and 17th Sts.) was once home to Andy Warhol’s Factory, frequented by the likes of Lou Reed, John Cale, Nico of the Velvet Underground, Truman Capote, and John Lennon. Here Warhol made many of his underground films, including Blow Job, Flesh, and I, Man.