The Baptistry of San Giovanni Battista was built between the 1310s and the 1320s, possibly by master-builder Camaino di Crescentino, alongside the monumental staircase rising to Piazza Jacopo della Quercia and containing the remains of the so-called "New Cathedral".The interior, divided into three rib-vaulted aisles, is frescoed throughout and constitutes one of the most fully representative examples of 15th century Sienese art anywhere. The twelve scenes illustrating the Twelve Articles of the Christian Faith were painted in the vaults by Lorenzo di Pietro, known as "Vecchietta", between 1447 and 1450. Each segment of the vault contains the depiction of one Article and is accompanied by an apostle in the bottom right-hand corner and a prophet in the bottom left-hand corner, identified by the inscription in the scroll that each figure holds in his hand.