Although not intended as such, this broad room is really an antechamber to the Sistine Chapel, reached by the Scala Regia. To the left of the entrance formerly stood the papal throne, which is now at the opposite side before the door leading to the Cappella Paolina.
The hall was begun under Pope Paul III by Antonio da Sangallo the Younger and was completed in 1573. The elegant barrel vault is provided with the highly graceful and very impressive plaster decorations of Perin del Vaga. The stucco ornaments over the doors are by Daniele da Volterra. The longitudinal walls are broken on the one side by two, and on the other by three, large doors, between which Livio Agresti, Giorgio Vasari and Taddeo Zuccari have introduced very powerful frescoes, whose effect is more than ornamental. Agresti's fresco has a political meaning, too: it represents Peter II of Aragon offering the Kingdom to Pope Innocent III.
They all depict momentous turning-points in the life of the Church, among others the return of Pope Gregory XI from Avignon to Rome, the Battle of Lepanto[disambiguation needed], the raising of the ban from Henry IV, and the reconciliation of Pope Alexander III with Frederick Barbarossa. This hall served originally for the reception of princes and royal ambassadors, so its name. Today the consistories are held in it, and an occasional musical recital in the presence of the pope; during a conclave it is a favourite promenade for the cardinals.