St. Peter's Basilica
When Michelangelo took over a building site in 1547, the nave of the old basilica was still standing and in use. There were four of the most enormous piers in the world standing where the western part of the old basilica had been. The building work had stopped for so long that weeds and bushes were growing out between the stones of the unfinished building as if it was a cliff. Michelangelo looked at all the plans that had been drawn by some of the greatest architects and engineers of the 16th century. He knew he could do whatever he liked but he had respect for the other designers, especially Bramante. He knew that he was expected to make a design that would be the symbol of the city of Rome, in the same way as Brunelleschi's dome was the symbol of Florence where Michelangelo had lived as a young man. He went back to the Greek Cross idea and re-drew Bramante's plan, making every part of it much stronger and simpler. It had to be strong enough to support the tallest dome in the world.