The series of Pontiffs ran along all the walls of the Chapel starting from that of the altar, at the centre of which was Christ and the first pope Peter, as well as Linus and Cletus. The four figures were lost when Michelangelo, by order of Paul III, painted the Last Judgement on this wall in 1536. The Pontiffs were arranged in pairs in niches beside the windows. Their series does not run along a wall, but alternates with the opposite wall. The authors of the series are the same as those of the cycles of the lives of Moses and of Christ, that is to say, Pietro Perugino, Sandro Botticelli, Cosimo Rosselli and Domenico Ghirlandaio. The position of the various personages differs only slightly. They are usually shown as a full figure in three-quarter profile with a book or scroll, or in the act of blessing.