 It was at the age of 72, in 1546, when Michelangelo first took hold of the unfinished rebuilding project started by Bramante.When Michelangelo died, the construction of the, then, Greek-cross section surrounding the Papal altar and the tomb of Peter had been completed only as far as the top of the drum.The dome then became completed, with some modifications, by Giacomo della Porta in 1590.