Union Square is now a beloved spot for alfresco lunches, high-octane protests and shopping. But it took a long time to reach today’s cheery, sunny status. Until 1831, the square was a graveyard for unidentified bodies, and didn’t enjoy the fruits of its revamp to public park until the 1860s, when labor and union organizers started staging protests. Designed by the planners of Central and Prospect Parks Frederick Law Olmstead and Calvert Vaux, Union Square became a cosmopolitan hub by the 1870s.