Main portal of San Petronio, Bologna (1425-30)

On 28 March 1425 Jacopo della Quercia was commissioned to design a complicated portal for the west façade of San Petronio, a late medieval church, located in the very heart of the papal states. He produced a design for a round-arched entranceway framed by historiated pilasters with Old Testament reliefs, eighteen busts of prophets, five New Testament reliefs in the architrave above the door, decorative colonnettes and a lunette above the door containing free-standing statues of the Virgin and Child, St Petronius and the patron, Cardinal Lodovico Alemanno, papal legate to Bologna. The Virgin and Child, the prophet busts, the lintel reliefs and the colonnettes were all carved first, during the period 1426-September 1428, while the Old Testament scenes and St Petronius were added in 1429/30.

Jacopo della Quercia's reliefs in Istrian stone for the Porta Magna of San Petronio in Bologna, his preoccupation during the last thirteen years of his life, are recognized as his masterworks.