text: Charles I, who ruled from 1331 to 1357, and was the son of François Grimaldi's cousin Rainier I, significantly enlarged the fortress by adding two large buildings: one against the eastern ramparts and the second looking out over the sea. This changed the appearance of the fortress, making it appear more of a fortified house than a fortress. The fortifications remained very necessary, for during the next three decades the fortress was alternately lost and regained by the Grimaldi to the Genoese. In 1341 the Grimaldi took Menton and then Roquebrune, thus consolidating their power and strength in the area. Subsequently, they strengthened not only the defences of the harbour but also their fortress on the Rocher. The Grimaldi's stronghold was now a power base from which the family ruled a large but very vulnerable area of land.
  For the next hundred years the Grimaldi defended their territory from attacks by other states which included Genoa, Pisa, Venice, Naples, France, Spain, Germany, England and Provence. The fortress was frequently bombarded, damaged, and restored. Gradually the Grimaldi began to make an alliance with France which strengthened their position. Now more secure, the Grimaldi lords of Monaco now began to recognise the need not only to defend their territory, but also to have a home reflecting their power and prestige.