Sforza Castle

Timeline

1. 1358

   Visconti Castle Begun

   Galeazzo II Visconti orders construction of the Castello di Porta Giova near the city walls, on the site of a Roman fortification.

2. 1447

   Ambrosian Republic Destroys the Castle

   After Filippo Maria Visconti dies without a male heir, the short-lived Ambrosian Republic tears down the Visconti seat in a republican gesture.

3. 1450

   Francesco Sforza Begins Reconstruction

   Mercenary captain Francesco Sforza defeats the republicans, takes the duchy of Milan, and immediately begins rebuilding the castle as his princely residence.

4. 1452

   Filarete Tower Designed

   Sculptor-architect Antonio Filarete is hired to design the central tower; the project marks the start of the castle's Renaissance phase.

5. 1494

   Ludovico il Moro's Court

   Ludovico Sforza becomes Duke of Milan and brings Leonardo da Vinci and Bramante to the castle, ushering in its artistic peak.

6. c. 1498

   Leonardo's Sala delle Asse Ceiling

   Leonardo da Vinci paints intertwined botanical motifs on the ceiling of the Sala delle Asse; in later centuries the work is whitewashed and forgotten.

7. 1499

   French Invasion Ends Ludovico's Reign

   Louis XII of France invades Milan and Ludovico is captured; the castle enters four centuries of foreign rule under successive powers.

8. 1521

   Filarete Tower Explodes

   While in use as a weapons depot, the Filarete Tower is destroyed by a gunpowder explosion, leaving the castle without its central crown for nearly 400 years.

9. 1796

   Napoleon Demolishes the Outer Walls

   Napoleon's conquest of Milan tears down the star-fort fortifications, and the surrounding area is reshaped into Piazza Castello and Piazza d'Armi.

10. 1893-1905

    Beltrami's Restoration

    Architect Luca Beltrami leads a major restoration; the Filarete Tower is rebuilt as a monument to King Umberto I from sixteenth-century drawings.

11. 1943

    Allied Bombing Damage

    Allied bombing during World War II severely damages the castle, but the BBPR firm leads postwar reconstruction adapted to civic museum use.

12. 2013

    Sala delle Asse Restoration Continues

    A new campaign of restoration on Leonardo's ceiling reveals fresh details of the botanical motifs hidden under centuries of whitewash.

13. 2025

    Leonardo's Hidden Passage Discovered

    A 2021-2023 digital survey identifies a second defensive tunnel below the castle that Leonardo had sketched around 1495, confirmed in 2025.

Detailed History

The history of Sforza Castle begins in 1358 when Galeazzo II Visconti ordered construction of the Castello di Porta Giova on the site of the Roman Castrum Portae Jovis, once the praetorian camp of Milan's late imperial capital. Under his successors Gian Galeazzo, Giovanni Maria, and Filippo Maria Visconti, it was expanded into a 200-meter square plan with four corner towers and walls up to seven meters thick, serving as the Visconti family's chief residence. Filippo Maria died without a male heir in 1447, and the short-lived Ambrosian Republic tore down the old Visconti castle in a republican rejection of dynastic rule. In 1450, Francesco Sforza — the mercenary captain who had married Filippo Maria's daughter Bianca Maria — took the duchy and immediately began rebuilding the castle as a princely residence. In 1452 he engaged Antonio Filarete to design the central tower, and construction continued under his son Galeazzo Maria. The tower of Bona of Savoy was added during her regency in 1476. When Ludovico 'il Moro' became Duke of Milan in 1494, the castle entered its cultural zenith: he summoned Leonardo da Vinci and Bramante, who painted frescoes in several rooms; Leonardo's ceiling of intertwined botanical motifs in the Sala delle Asse, completed around 1498, is the most celebrated survival. The invasion of Louis XII of France in 1499 ended Ludovico's reign and began four centuries of foreign control. After the French victory at Marignano in 1515, Maximilian Sforza took refuge in the castle but capitulated when Francis I's sappers mined its foundations. In 1521, while serving as a weapons depot, the Filarete Tower exploded. From 1550 it was rebuilt as a twelve-bastion star fort whose external defenses extended three kilometers and covered 25.9 hectares. Napoleon's conquest of Milan in 1796 demolished most of the outer fortifications, and the area was reshaped as Piazza Castello and the Piazza d'Armi parade ground. After Italian unification in 1859, the castle was transferred to the city of Milan and the parade grounds became Parco Sempione. Restoration directed by Luca Beltrami began in 1893; between 1900 and 1905 the Filarete Tower was rebuilt as a monument to King Umberto I. Allied bombing in 1943 damaged the castle, but BBPR architects led postwar reconstruction for museum use.

Cultural Significance

Sforza Castle was the political, cultural, and military heart of the duchy of Milan under two great North Italian dynasties — the medieval Visconti and Renaissance Sforza — and remains a symbol of Lombard sovereignty. Inside, seven civic museums (the Museo Pieta Rondanini, Museum of Ancient Art, Pinacoteca, Egyptian Museum, Museum of Decorative Arts, Museum of Musical Instruments, and Museum of Antique Furniture) hold one of the richest cultural collections in northern Italy. Among them, Michelangelo's unfinished Rondanini Pieta, carved until six days before his death in 1564, and the botanical ceiling Leonardo painted in the Sala delle Asse around 1498 are treasures of global art history. The succession of foreign rulers — French, Spanish, Austrian, and French again — makes the castle a record of Milan as the 'crossroads of Europe.' Beltrami's restoration project is a landmark of European historicist architecture, and its method of reconstructing lost forms from documentary evidence influenced conservation theory worldwide. As a symbol of the Risorgimento, the castle remains a focus of civic identity for the people of Milan today.

Architectural Details

Sforza Castle has a square plan roughly 200 meters on each side, with circular and rectangular towers at the four corners and walls up to seven meters thick. The southern facade is dominated by the Filarete Tower (about 70 meters tall), flanked by the round Torrione di Santo Spirito at the southeast and Torrione del Carmine at the southwest; square towers hold the northern corners. The central facade is built in red Lombard brick with marble inserts and heraldic reliefs, combining medieval masonry and Renaissance ornamentation. Inside, two main courtyards — the Piazza d'Armi and Cortile della Rocchetta — are separated by inner ranges. Loggias attributed to Filarete and Bramante run around the Rocchetta; the Corte Ducale stands around the second. The outer defenses were rebuilt in the sixteenth century as a twelve-bastion star fort with main walls, moats, and glacis, demolished in the nineteenth century. The roof is clad in red terracotta tiles; principal materials are local red brick and limestone, with Candoglia marble accents. Beltrami's 1893-1905 restoration reconstructed the Filarete Tower from documentary research, and the Sala delle Asse ceiling, rediscovered in 1893, has undergone restoration campaigns to 2013.