Giangaleazzo Visconti (reigned 1378-1402) fortified the Rocca di Porta Giovia (1358-1368), thus founding the Castello di Porta Giovia (later Castello Sforzesco), which he made his official seat. Under Francesco Sforza I, in 1455, the cylindrical towers of the Castello Sforzesco were begun. The main square entrance tower is called Torre del Filarete after the architect. This was rebuilt (restored) between 1900 and 1905 as a monument to King Umberto I. The castle has gone through a series of damages and restoration programs and today houses several museums including the Pinacoteca del Castello Sforzesco.