sentences:  The Arsenal, a large military-industrial complex tasked with the production of cannons and other weapons for the royal armies, was established to the south of the Bastille by Francis I, and substantially expanded under Charles IX.An arms depot was later built above the Porte Saint-Antoine, all making the Bastille part of a major military centre.During the 1550s, Henry II became concerned about the threat of an English or Holy Roman Empire attack on Paris, and strengthened the defences of the Bastille in response.