Final answer:
Michelangelo modified Bramante's original plan for Saint Peter's Basilica by adopting a Greek Cross plan and adding massive exterior masonry, which contributed to a more symmetrical and monumental architectural design.
Step-by-step explanation:
Michelangelo made significant changes to Bramante's original plan for Saint Peter's Basilica. The most notable modification was a shift to a Greek Cross plan, emphasizing a central dome and creating a more symmetrical design.
Michelangelo's revisions produced a building with an imposing exterior masonry, contributing to the basilica's monumental scale and distinct architectural presence. Unlike Bramante's plan, which proposed a square enclosed Greek cross form, Michelangelo filled in each corner with stairwells or small vestries, creating a continuous wall surface. Furthermore, the giant order of Corinthian pilasters that Michelangelo designed are set at varied angles, adding a dynamic form to the structure. His design ensured that St. Peter's Basilica would be a structure of colossal proportions and grandeur.Though Michelangelo's plan for the basilica was itself later altered by other architects such as Carlo Maderno and Gian Lorenzo Bernini, it is Michelangelo's dome and Greek Cross plan that are most associated with the vision of Saint Peter's Basilica as we know it today.