Which room in Milan's Sforza Castle did Leonardo decorate with a tree-canopy illusion?

Leonardo da Vinci decorated the Sala delle Asse in Milan’s Sforza Castle with a trompe-l’œil tree canopy. The room’s name means “Room of the Wooden Boards,” probably referring to wooden paneling that once covered its walls.

Leonardo worked on the decoration around 1498 for Ludovico Sforza, the Duke of Milan. Painted trunks rise from the walls, while branches, leaves, fruit, and interlacing cords spread across the vault. The design creates the illusion that visitors are standing beneath a natural pergola rather than inside a fortified palace room.

Mulberry trees are central to the imagery. Ludovico promoted mulberry cultivation because the leaves fed silkworms, supporting Milan’s silk industry. The trees therefore carried both practical and political symbolism: they evoked prosperity, stable government, and the duke’s patronage. The room also includes a painted monochrome of roots and rocks, extending the illusion from the canopy down into the structure of the walls.

The decoration suffered after the castle was repurposed and the room was covered over. Traces were rediscovered during restoration in the 1890s, and later conservation has continued to separate Leonardo’s surviving work from modern repainting.