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. Peperino blocks from the Tabularium were re-used in the left side of the palace and a corner of the bell tower. It now houses the Roman city hall. Its double ramp of stairs was designed by Michelangelo. This double stairway to the palazzo replaced the old flight of steps and two-storied loggia, which had stood on the right side of the palace. The staircase cannot be seen solely in terms of the building to which it belongs but must be set in the context of the piazza as a whole.