With help from The Map Guy
Above is a drawing of the Old St. Peter's Basilica in Rome - built by Constantine in the 4th Century AD. It was built at the place where St. Peter died, which was a Roman circus, where chariot races and gladiator fights took place. Around 1450, the pope decided tear it down because it was in a state of disrepair. From 1475-1483 they built a famous chapel and when it was completed, the pope hired Botticelli, Ghirlandaio, Rosselli, and Perugino to paint the walls on the sides of the chapel. They painted the ceiling blue with stars. In 1508, another pope hired Michelangelo to paint frescoes of the twelve apostles on the ceiling. After he started the work, Michelangelo decided that he didn't like them and came up with a different idea that we can see today. He finished the frescoes in 1512.
The groundbreaking for the new St. Peter's Basilica was in 1506 and it was consecrated in 1626.