Union Square is one of the most important and most crowded epicenters in New York City. It was named because it marked the place where Bowery and Broadway met, making it one of the most important intersections in the world during the 19th Century. Union Square park has long been a site of political activism, and now boasts a fantastic Green Market. Many interesting buildings line Union Square, including the old location of Tammany Hall, as well as the Decker Building, the site of Warhol's factory.