Following the proclamation of the dogma of the Immaculate Conception by Pius IX, which took place on 8 December 1854, the pontiff decide to celebrate the event with a cycle of frescoes.
The large room adjacent to the Raphael's Rooms was chosen, and the task was assigned to Francis Podesti (1800-1895), a painter originally from Ancona but rooted in the Roman artistic and academic panorama. The artist, along with his team of workers, worked on the commission from 1856 to 1865, planning it and following its execution in all its aspects: the wooden doors and window frames and the inlaid marble work, as well as the installation of the Roman mosaic from Ostia Antica, purchased specifically for this space.
The pictorial decoration proceeds from the ceiling, with allegorical scenes alluding to the virtues of the Virgin; it continues along the northern wall with the homage of the continents to the Church enthroned; it continues on the west wall, devoted to the Discussion of dogma in St. Peter’s Basilica, and concludes on the east wall, with the Coronation of the Image of Mary, an event following the Proclamation, which took place in St. Peter’s. Podesti, who was present, included a self-portrait here.