text: Throughout the 15th century, both the fortress and the Rocher continued to be extended and further defended until it became a garrison accommodating some 400 troops. The slow transformation from fortified house to palace (Illustration 7) began during this era, first with building by Lamberto Grimaldi, Lord of Monaco (who between 1458 and 1494 was "a noteworthy ruler who handled diplomacy and the sword with equal talent"), and then by his son Jean II. This period saw the extension of the east side of the fortress with a three–floored wing, guarded by high scalloped walls connecting the bastion towers—St Mary (M in Illustration 7), Middle (K) and South (H). This large new wing contained the palace's principal room, the State Hall (today known as the Guard Room). Here the princes carried out their official business and held court. Further, more luxurious, rooms complete with balconies and loggias were designed for the private use of the Grimaldi family. In 1505 Jean II was killed by his brother Lucien.
  Fortress to palace
  Lucien I (1505–1523)
  Jean II was succeeded by his brother Lucien I. Peace did not reign in Monaco for long; in December 1506 14,000 Genoese troops besieged Monaco and its castle, and for five months 1,500 Monégasques and mercenaries defended the Rocher before achieving victory in March 1507. This left Lucien I to walk a diplomatic tightrope between France and Spain in order to preserve the fragile independence of the tiny state which was in truth subject to Spain. Lucien immediately set about repairing the ravages of war to the fortified palace which had been damaged by heavy bombardment. To the main wing (see Illustrations 3 & 7 – H to M ), built by Prince Lambert and extended during the reign of Jean II, he now added a large wing (H to C) which today houses the state apartments.