Sistine Chapel ceiling of the chapel, now closed, and those above the High Altar covered by the Last Judgement. Above each window is an arched shape, referred to as a lunette and above eight of the lunettes at the sides of the chapel are triangular "spandrels" filling the spaces between the side pendentives and the vault, the other eight lunettes each being below one of the corner pendentives. Michelangelo was commissioned to paint these areas as part of the work on the ceiling. The structures form visual bridges between the walls and the ceiling, and the figures which are painted on them are
Sistine Chapel congregations. These included the Christmas Day and Easter masses, at which the Pope himself was the celebrant. The other 27 masses could be held in a smaller, less public space, for which the "Cappella Maggiore" was used before it was rebuilt on the same site as the Sistine Chapel. The "Cappella Maggiore" derived its name, the Greater Chapel, from the fact that there was another chapel also in use by the Pope and his retinue for daily worship. At the time of Pope Sixtus IV, this was the Chapel of Pope Nicholas V, which had been decorated by Fra Angelico.