San Piero a Grado

This guide to San Piero a Grado near Pisa opens with a puzzle: why builders pressed sixty-four foreign clay bowls, called bacini, into the highest walls of a basilica raised between the tenth and twelfth centuries over a Pisan harbor that was already silting up. It follows the modern ceramic scientists who finally studied the glaze, clay and painted patterns and traced each bowl back to a workshop somewhere around the Mediterranean, from Tunisia to Sicily, Majorca and Islamic Spain. Look up at the blind arches as you walk the nave, where the bowls were set into the stone as a kind of message meant to be read from a distance.