Built during the 13th and 14th centuries, the Palazzo Senatorio ("Senatorial Palace") stands atop the Tabularium, which had once housed the archives of ancient Rome. It now houses the Roman city hall. Its double ramp of stairs was designed by Michelangelo. The fountain in front of the staircase features the river gods of the Tiber and the Nile as well as Dea Roma (Minerva). Its bell-tower was designed by Martino Longhi the Elder and built between 1578 and 1582.