Madison Square is a park located at Fifth Ave. and 23RD St. in mid-town Manhattan. From 1879 until 1925 the arena still known as Madison Square Garden was located there. And in the last months of 1918 it was decided to build a victory arch there, too, an American Arc de Triomphe. However, there was insufficient time to build a permanent structure before the New York boys came home in 1919, so the arch was constructed of wood and plaster instead. You can read the whole story here.