Dome of the Old Sacristy

The Old Sacristy shows the continuation of medieval building tradition in the main walls, which serve both bearing and weatherproofing functions, while the facing elements in pietra serena (the pilaster strips, capitals, trabeation, and arch frame) are innovative in their formal appearance, imitating structural functions while in reality they are merely ornamental. The structure of the umbrella dome, with its stone radial ribs and conoidal masonry webs, also harks back to medieval types.