Most visitors to Castello Sforzesco know one thing about Leonardo da Vinci's connection to the castle: the Sala delle Asse, the painted ceiling in the Rocchetta tower. It's extraordinary — a trompe-l'oeil canopy of intertwined mulberry trees, commissioned around 1498 by Ludovico il Moro. But to reduce Leonardo's 17 years at the Sforza court to a single ceiling is to miss almost everything.
The Invitation to Milan
Leonardo arrived in Milan in 1482, aged 30, bearing a letter of introduction to Ludovico il Moro. The letter — famously preserved in the Codex Atlanticus — did not lead with his painting. It led with his engineering. Leonardo outlined his abilities as a military architect, bridge builder, cannon designer, and siege engineer. He mentioned painting almost as an afterthought, in the final paragraph.
In painting, I can do what anyone else can do — and more. In bronze and marble sculpture, likewise. But in the other arts I have described, I believe I have no equal.
This was not modesty. It was a calculated pitch. Ludovico needed engineers. Leonardo needed a patron. The arrangement suited both.
The Moat and the Defences
One of Leonardo's first major commissions at the castle was the redesign of its defensive moat system — at Ludovico's request in 1482. His notebooks from this period contain detailed hydraulic studies, moat geometry calculations, and designs for defensive outworks that were never fully built but that show him thinking deeply about the problem.
The moat itself — drained by Napoleon in 1796 — was partly shaped by Leonardo's proposals. The moat gardens you can walk around today follow the course he helped design.
The Sala delle Asse
The painted ceiling is real and it is astonishing. Approximately 1498: Leonardo covers the vaulted ceiling of the tower room with a dense canopy of mulberry branches (moro — a pun on Ludovico's name), their roots wrapping around the base of the columns and their branches interweaving across the vault.
Restoration work beginning in 2013 revealed far more than anyone expected — a monochrome preparatory drawing beneath the painted surface, showing roots and rock formations that Leonardo blocked in before adding colour. The full restoration is still ongoing, with some areas still being uncovered.
The Works That Didn't Survive
The Sala delle Asse survived largely because it was painted onto the vault itself. Many of Leonardo's other works at the castle did not. The Sala delle Asse's companion paintings on the walls are lost. The decorative schemes for the ducal apartments — documented in contemporary accounts — are gone. Leonardo's stage designs and mechanical devices for Sforza court entertainments survive only in his notebooks.
What we have is a fraction of what existed. The 17 years left traces rather than monuments — except for the ceiling, and the notebooks, and the Codex Atlanticus, much of which was produced during these Milan years.