Castello Sforzesco used to be the seat and residence of the ruling family of Milan and now houses several of the city's museums and art collections. The original construction on the site began in the 14th century. In 1450, Francesco Sforza began reconstruction of the castle, and it was further modified by later generations. A number of these rooms originally had elaborate internal decoration - the best known of these being the Sala Delle Asse with surviving ceiling paintings by Leonardo da Vinci. After the French victory in the 1515 Battle of Marignano, the defeated Massimiliano Sforza, his Swiss mercenaries and the cardinal-bishop of Sion retreated into the Castello Sforzesco. However, King Francis I of France followed them into Milan, and his sappers placed mines under the castle's foundations, whereupon the defenders submitted. After the unification of Italy in the 19th century, the restoration of the castle was started following its transfer from military use to the city of Milan. The restoration work was directed by Luca Beltrami. The central Filarete tower above the main city entrance was rebuilt between 1900 and 1905 as a monument to King Umberto I. The castle was severely damaged as a result of the allied bombardment of Milan in 1943 during World War II. The post-war reconstruction of the building for museum purposes was undertaken by the BBPR architectural partnership. (Text based on Wikipedia).