The Papal Basilica of Saint Peter in the Vatican, or simply Saint Peter's Basilica, is a church built in the Renaissance style located in Vatican City, the papal enclave that is within the city of Rome, Italy. It was initially planned by Pope Nicholas V and then Pope Julius II to replace the aging 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.