With a capacity of over 60,000 people, St. Peter’s Basilica is the one of the world’s largest churches as well as one of the world’s holiest Catholic sites. Begun by Pope Julius II in 1506 and completed more than a century later, it was built to replace Old St. Peter’s, erected by Constantine over Peter’s traditional burial site. Michelangelo and Bernini were among its many architects, and a number of their masterpieces adorn its interior. Why is St. Peter’s not considered a cathedral? Discuss