Twenty third Regiment Armory is a historic National Guard armory building located in Crown Heights, Brooklyn, New York, New York. It is a brick and stone castle-like structure built between 1891 and 1895, designed to be reminiscent of medieval military structures in Europe in the Romanesque Revival style.
It consists of a three-story administration building with an attached drill shed. It is constructed of deep red pressed brick, brownish red Potsdam stone, and red terra cotta detail. It features a series of circular corner towers, the tallest of which is 136 feet in height. It was listed on the National Register of Historic Places in 1980.