Restoration of the Sistine Chapel frescoes smoke and exhaust fumes of the city, being "much dirtier than the ceiling proper". The building was a little unstable and had already shifted considerably prior to Michelangelo's work of 1508, causing cracking of the ceiling, the crack in the "Judith" pendentive being so large that it had to be filled with bricks and mortar before painting. The upper part of the ceiling provided Michelangelo an irregular surface due to cracks and water seepage. Continued ingress of water from the roof and from unroofed exterior walkways above the ceiling level had caused seepage which carried down salts from the building
Sistine Chapel ceiling "Life of Moses" on the left side. It was carried out by some of the most renowned Renaissance painters: Botticelli, Ghirlandaio, Perugino, Pinturicchio, Signorelli and Cosimo Rosselli. The upper level of the walls contains the windows, between which are painted pairs of illusionistic niches with representations of the first thirty-two popes. A draft by Matteo d'Amelia indicates that the ceiling was painted blue like that of the Arena Chapel and decorated with gold stars, possibly representing the zodiacal constellations. It is probable that, because the chapel was the site of regular meetings and Masses of an elite body of officials