Leonardo da Vinci painted The Last Supper in the refectory of the Dominican convent of Santa Maria delle Grazie in Milan between about 1495 and 1498. Ludovico Sforza, duke of Milan, commissioned the work during a broader rebuilding of the church and convent as a dynastic setting. Leonardo placed Christ and the apostles across the end wall at the moment Christ announces that one disciple will betray him, turning a familiar monastic dining-room subject into an intense study of reaction, gesture, and group psychology.

The composition organizes the apostles in four groups of three around the still figure of Christ. Lines of the ceiling and walls converge toward him, extending the real refectory into the painted space. Leonardo worked slowly and revised repeatedly. Instead of applying pigment to wet plaster in true fresco, he used an experimental mixed technique on a dry prepared wall. That choice allowed subtle modeling and changes, but it bonded poorly with the masonry and began to deteriorate within decades of completion.

The mural endured humidity, unstable materials, overpainting, changes to the room, and a doorway cut through the lower center in the seventeenth century. Repeated restorers attempted to strengthen or repaint damaged passages, sometimes obscuring surviving work. French occupation brought additional misuse of the refectory. In August 1943 Allied bombing destroyed much of the surrounding convent, but sandbags and bracing protected the mural wall. The exposed room nevertheless suffered from weather and vibration before it could be enclosed again.

A major conservation campaign led by Pinin Brambilla Barcilon lasted from 1977 to 1999. Conservators stabilized the surface, removed later repaint where possible, and used scientific examination to distinguish Leonardo's surviving pigment from losses and earlier interventions. The result does not recreate a pristine original. Large areas remain abraded or missing, and careful neutral integrations help the fragmented image read coherently. Environmental controls, filtered air, limited group sizes, and timed visits now reduce dust, humidity changes, and carbon dioxide around the painting.

The Cenacolo is significant because its history of damage is inseparable from its artistic achievement. Visitors see Leonardo's original material, old alterations, modern conservation, and unavoidable absence on the same wall. The adjoining church and convent place the painting within the religious and political world that produced it, rather than treating it as a movable museum picture. Its survival demonstrates how experimental technique can create extraordinary effects while imposing permanent conservation limits, and why responsible interpretation must acknowledge both masterpiece and fragile archaeological surface.