The building consists of a central pavilion with two projecting wings. The entrance, reached by a long flight of steps, has figured prominently in civic events for over a century and a half. There is a columned entrance portico capped by a balustrade, and another balustrade at the roof. The domed tower in the center was rebuilt in 1917 after the last of two major fires. The original Massachusetts marble facade, quarried from Alford, Massachusetts, and complemented with brownstone on the rear elevation, had deteriorated over time from pollution and pigeons. It was completely reclad in Alabama limestone above a Missouri granite base in 1954–56 by Shreve, Lamb & Harmon, architects of the Empire State Building.