St Peters at Vatican City

The Papal Basilica of Saint Peter in the Vatican (Latin: Basilica Sancti Petri), officially known in Italian as Basilica Papale di San Pietro in Vaticano and commonly known as Saint Peter's Basilica, is a Late Renaissance church located within Vatican City. Saint Peter's Basilica has the largest interior of any Christian church in the world.[1] While it is neither the mother church of the Roman Catholic Church nor the cathedral of the Bishop of Rome, Saint Peter's is regarded as one of the holiest Catholic sites. It has been described as "holding a unique position in the Christian world"[2] and as "the greatest of all churches of Christendom".[3]

In Roman Catholic tradition, the basilica is the burial site of its namesake Saint Peter, one of the twelve apostles of Jesus and, according to tradition, was the first Bishop of Rome and therefore first in the line of the papal succession. Tradition and some historical evidence hold that Saint Peter's tomb is directly below the altar of the basilica. For this reason, many Popes have been interred at St Peter's since the Early Christian period. There has been a church on this site since the 4th century. Construction of the present basilica, over the old Constantinian basilica, began on 18 April 1506 and was completed on 18 November 1626.[4]

St Peter's is famous as a place of pilgrimage, for its liturgical functions and for its historical associations. It is associated with the papacy, with the Counter-reformation and with numerous artists, most significantly Michelangelo. As a work of architecture, it is regarded as the greatest building of its age.[5] Saint Peter's is one of the four churches of Rome that hold the rank of Major Basilica. Contrary to popular misconception, it is not a cathedral as it is not the seat of a bishop; the cathedra of the Bishop of Rome is located in the Archbasilica of St. John Lateran.