Christ the Redeemer alongside Saints Peter, the Virgin Mary, John the Evangelist and Paul

Most panels this old reach us anonymous and undated, so this one is a small piece of luck: the painter signed it and dated it. The name Meliore is worked into the gold ground, and the year 1271 is spelled out in Roman numerals across the panels of Saint Peter and Saint Paul. Christ the Redeemer sits at the centre, blessing, with the Virgin and Saints Peter, John the Evangelist and Paul beside him, each a half figure under a little trefoil arch. The shape is the surprising part. It is a long rectangle rising to a point in the middle, one of the earliest altar panels built this way, and those framed arcades look ahead to the big multi-panel polyptychs Italy would love in the next century. The gilded seraphim tucked between the arches were added later, roughly 200 years after Meliore laid down his gold.