Carlo Maderno in the context of "Baroque architecture"

The Papal Basilica of Saint Peter in the Vatican (Italian: Basilica Papale di San Pietro in Vaticano), or simply St. Peter's Basilica (Latin: Basilica Sancti Petri; Italian: Basilica di San Pietro [baˈziːlika di sam ˈpjɛːtro]), 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.

Designed principally by Donato Bramante, Michelangelo, and Carlo Maderno, with piazza and fittings by Gian Lorenzo Bernini, Saint Peter's is one of the most renowned works of Italian Renaissance architecture and is the largest church in the world by interior measure. While it is neither the mother church of the Catholic Church nor the cathedral of the Diocese of Rome (these equivalent titles being held by the Archbasilica of Saint John Lateran in Rome), Saint Peter's is regarded as one of the holiest Catholic shrines. It has been described as "holding a unique position in the Christian world", and as "the greatest of all churches of Christendom".

A façade or facade (/fəˈsɑːd/ ; ) is the front part or exterior of a building. It is a loanword from the French façade (pronounced [fasad]), which means "frontage" or "face".

In architecture, the façade of a building is often the most important aspect from a design standpoint, as it sets the tone for the rest of the building. From the engineering perspective, the façade is also of great importance due to its impact on energy efficiency. For historical façades, many local zoning regulations or other laws greatly restrict or even forbid their alteration.

St. Peter's Square (Latin: Forum Sancti Petri, Italian: Piazza San Pietro [ˈpjattsa sam ˈpjɛːtro]) is a large plaza located directly in front of St. Peter's Basilica in Vatican City, the papal enclave in Rome, directly west of the neighborhood (rione) of Borgo. Both the square and the basilica are named after Saint Peter, an apostle of Jesus whom Catholics consider the first Pope.

At the centre of the square is the Vatican obelisk, an ancient Egyptian obelisk erected at the current site in 1586. Gian Lorenzo Bernini designed the square almost 100 years later, including the massive Tuscan colonnades, four columns deep, which embrace visitors in "the maternal arms of Mother Church". A granite fountain constructed by Bernini in 1675 matches another fountain designed by Carlo Maderno in 1613.