In the right transept, protected by a wrought iron grille made by the master craftsman Drea di Lavaccio of Colle in the seventeenth century, is the chapel of the Holy Nail, built at the behest of the first Bishop of Colle, Usimbardo Usimbardi, at the same time as the cathedral in 1592. Inside the chapel, the marble tabernacle attributed to Domenico Rosselli holds the precious relic that, . . .