44 Union Square, also known as 100 East 17th Street and the Tammany Hall Building, is a three-story building at 44 Union Square East in Union Square, Manhattan, in New York City. It is at the southeast corner of Union Square East/Park Avenue South and East 17th Street. The neo-Georgian structure was erected in 1928–1929 and designed by architects Tho…44 Union Square, also known as 100 East 17th Street and the Tammany Hall Building, is a three-story building at 44 Union Square East in Union Square, Manhattan, in New York City. It is at the southeast corner of Union Square East/Park Avenue South and East 17th Street. The neo-Georgian structure was erected in 1928–1929 and designed by architects Thompson, Holmes & Converse and Charles B. Meyers for the Tammany Society political organization, also known as Tammany Hall. It is the organization's oldest surviving headquarters building.