Plan of St. Peter's, from "Speculum Romanae Magnificentiae"

Antonio da Sangallo the Younger, also known as Antonio Cordiani, was an Italian architect active during the Renaissance, mainly in Rome and the Papal States. He worked on the design of St. Peter's Basilica in the Vatican City, and was also an engineer who restored several buildings. His success was greatly due to his contracts with renowned artists during his time. Sangallo died in Terni, Italy, and was buried in St. Peter’s Basilica.