Castello Sforzesco is one of the largest citadels in Europe, a massive red-brick fortress rising at the northwestern edge of Milan's historic centre. Its origins trace to 1358, when Galeazzo II Visconti built a fortified residence on the site. After a period of demolition during the short-lived Ambrosian Republic, Francesco Sforza — who seized the Duchy of Milan in 1450 — ordered a complete reconstruction beginning in 1451. The result was a new dynastic seat of power that would define Milan for centuries. The iconic central tower, the Torre del Filarete, collapsed in 1521 due to a gunpowder explosion and was faithfully reconstructed between 1900 and 1905 by architect Luca Beltrami, who also led the castle's broader neo-Renaissance restoration during that period.
Under Ludovico Sforza ("il Moro"), who ruled from 1481, the castle became one of the most brilliant courts in Renaissance Italy. Leonardo da Vinci spent nearly two decades in Milan — from around 1482 to 1499 — serving as court engineer and artist. He contributed frescoes to rooms inside the castle, most notably the interlaced vine and mulberry ceiling decorations in the Sala delle Asse, which survive in partially restored form today. The castle fell to French forces in 1499, ending Sforza rule, and passed through Spanish and then Austrian hands before Napoleon's troops arrived in 1796. It served as a military barracks for much of the 18th and 19th centuries, sustaining significant damage before its civic reinvention at the turn of the 20th century.
