The Castle Square Theatre in Boston, Massachusetts, was located on Tremont Street in the South End. The building existed until its demolition in 1933. The theatre was the Boston home of Henry W. Savage's Castle Square Opera Company, a touring opera company which had theaters in other cities like Chicago and New York City, but took its name from th…The Castle Square Theatre in Boston, Massachusetts, was located on Tremont Street in the South End. The building existed until its demolition in 1933. The theatre was the Boston home of Henry W. Savage's Castle Square Opera Company, a touring opera company which had theaters in other cities like Chicago and New York City, but took its name from the Boston theatre.