Saint Peter’s Basil­i­ca, or San Pietro in Vat­i­cano as it’s also known, was built between 1506 and 1626 on the site of the Old Saint Peter’s Basil­i­ca. The old church was estab­lished by the Emper­or Con­stan­tine the Great in 324 A.D. The site of the old basil­i­ca was cho­sen because it was believed to be the bur­ial place of St. Peter, who is tra­di­tion­al­ly con­sid­ered to be the first Bish­op of Rome and there­fore the first pope and leader of Chris­ten­dom.