The Cathedral of San Zeno dates from the 12th century and presents a serene Romanesque façade in green and white marble to the piazza. The interior is severe by Italian standards — dark, relatively undecorated, with heavy stone columns and a few good frescoes in the side chapels. The reason to come is the Altar of Saint James in the Chapel of Saint James on the left: an extraordinary silver altarpiece that is one of the great works of Italian medieval craftsmanship, with over 628 figures worked in silver on a single altar panel.
The altar was constructed between 1287 and around 1456, with dozens of different artists contributing over the centuries. The right side is attributed to Brunelleschi in his early career as a goldsmith before he turned to architecture. The level of detail — figures as small as a fingernail, each one individually rendered — rewards close examination. The separate treasury contains other ecclesiastical silver and textiles from the medieval period.