The first stage in the decoration of the Sistine Chapel was the painting of the ceiling in blue, studded with gilt stars,[1] and with decorative borders around the architectural details of the pendentives. This was entirely replaced when Michelangelo came to work on the ceiling in 1508.

Of the present scheme of frescos, the earliest part is that of the side walls. They are divided into three main tiers. The central tier of the walls has two cycles of paintings, which complement each other, The Life of Moses and The Life of Christ. They were commissioned in 1480 by Pope Sixtus IV and executed by Domenico Ghirlandaio, Sandro Botticelli, Pietro Perugino, Cosimo Rosselli and their workshops. They originally ran all round the walls, but have since been replaced on both end walls.

The project was perhaps supervised by Perugino, who arrived at the chapel prior to the Florentines. It is probable that the commission of Ghirlandaio, Botticelli and Roselli was part of a reconciliation project between Lorenzo de' Medici, the de facto ruler of Florence, and Pope Sixtus IV. The Florentines started to work in the Sistine Chapel in the spring of 1481.

Beneath the cycles of The Life of Moses and The Life of Christ, the lower level of the walls is decorated with frescoed hangings in silver and gold. Above the narrative frescos, the upper tier is divided into two zones. At the lower level of the windows is a Gallery of Popes painted at the same time as the Lives. Around the arched tops of the windows are areas known as the lunettes which contain the Ancestors of Christ, painted by Michelangelo as part of the scheme for the ceiling.

The ceiling was commissioned by Pope Julius II and painted by Michelangelo between 1508 and 1512. The commission was originally to paint the twelve apostles on the triangular pendentives which support the vault; however, Michelangelo demanded a free hand in the pictorial content of the scheme. He painted a series of nine pictures showing God's Creation of the World, God's Relationship with Mankind, and Mankind's Fall from God's Grace. On the large pendentives he painted twelve Biblical and Classical men and women who prophesied that God would send Jesus Christ for the salvation of mankind, and around the upper parts of the windows, the Ancestors of Christ.

In 1515, Raphael was commissioned by Pope Leo X to design a series of ten tapestries to hang around the lower tier of the walls.[2] The tapestries depict events from the Life of St. Peter [four tapestries] the Life of St. Paul [six tapestries], the founders of the Christian Church in Rome as described in the Gospels and the Acts of the Apostles. Work began in mid-1515. Due to their large size, manufacture of the hangings was carried out in Brussels, and took four years under the hands of the weavers in the shop of Pieter van Aelst.[3] Raphael's tapestries were looted during the Sack of Rome in 1527 and were either burnt for their precious metal content or were scattered around Europe. In the late 20th century, a set was reassembled from several further sets that had been made after the first set, and displayed again in the Sistine Chapel in 1983. The tapestries continue to be used at occasional ceremonies of particular importance. The full-size preparatory cartoons for seven of the 10 tapestries are known as the Raphael Cartoons and are in London.[4]

At this point, the decorative scheme displayed a consistent iconographical pattern. The tier of Popes, which, in the scheme intended by Pope Julius, would have appeared immediately below the Twelve Apostles, would have emphasised the apostolic succession. It has been argued that the present scheme shows the two Biblical Testaments merged in order to reveal the Old predicting and framing the New, synthesizing the logic of the Christian Bible.[5]

This was disrupted by a further commission to Michelangelo to decorate the wall above the altar with The Last Judgment, 1537–1541. The painting of this scene necessitated the obliteration of two episodes from the Lives—the Nativity of Jesus and the Finding of Moses; several of the Popes; and two sets of Ancestors.