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. One of his most popular projects that he worked on designing is St. Peter’s basilica in the Vatican City. He was also an engineer who worked on restoring 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.

The Papal Basilica of Saint Peter in the Vatican, or simply Saint Peter's Basilica, is a church of the Italian High Renaissance located in Vatican City, an independent microstate enclaved within the city of Rome, Italy. It was initially planned in the 15th century by Pope Nicholas V and then Pope Julius II to replace the ageing Old St. Peter's Basilica, which was built in the fourth century by Roman emperor Constantine the Great. Construction of the present basilica began on 18 April 1506 and was completed on 18 November 1626.