Macy's is a United Department Store (United Department Store acquired Macy's in 1994). Macy's is a famous department store chain in the United States. Macy's flagship store is located in Hynold Square, New York City. (Herald Square) Macy's was advertised as the "world's largest store" when it opened on 7th Avenue in 1924. Macy's also has two national flagship stores, Union Square in San Francisco and State Street in Chicago.