The Basilica of Saint Peter from Castel Sant'Angelo. The Basilica of Saint Peter, officially known in Italian as the Basilica di San Pietro in Vaticano and commonly called Saint Peter's Basilica, is one of four major basilicas of Rome (St. John Lateran, St. Peter's, Santa Maria Maggiore and St. Paul outside the Walls). It is the most prominent building inside the Vatican City and built on the ruins of Old Saint Peter's Basilica. Its dome is also a dominant feature of the Roman skyline. Saint Peter's is also incidentally the patriarchal basilica of Constantinople, whereas the Lateran Basilica is the patriarchal basilica of Rome. Possibly the largest church building in Christianity.
Although the Vatican basilica is not the Pope's official seat (Saint John Lateran), it is most certainly his principal church, as most Papal ceremonies take place at St. Peter's due to its size, proximity to the Papal residence, and location within the Vatican City walls. The basilica also holds a relic of the Cathedra Petri, which is, according to Catholic tradition, the episcopal throne of the basilica's namesake when he supposedly led the Roman church, but which is no longer used as the Papal cathedra. It is believed that a piece of this cathedra, or chair, is contained within the altarpiece, designed by Bernini.

Details

Main article: Saint Peter's tomb Burial site of St Peter

Main article: Old Saint Peter's Basilica Old St. Peter's
There are over 100 tombs located within St. Peter's Basilica, many located in the Vatican grotto, beneath the Basilica. These include 91 popes, St. Ignatius of Antioch, and the composer Giovanni Pierluigi da Palestrina. Exiled Catholic British royalty James Francis Edward Stuart and his two sons, Charles Edward Stuart and Henry Benedict Stuart, are buried here, due to being granted asylum by Pope Clement XI. The most prominent woman entombed is Christina of Sweden, who abdicated her throne in order to convert to Catholicism. The most recent interment was Pope John Paul II, on April 8, 2005. Beneath, near the crypt, is the recently-discovered vaulted fourth-century "Tomb of the Julii".

Other burials
For work on St Peter's, Pope Nicholas V bought 2,522 cartloads of stone from the badly damaged Roman Colosseum. Quarrying of stone for the Colosseum had, in turn, been paid for with treasure looted at the Fall of Jerusalem and destruction of the temple by the emperor Vespasian's general (and the future emperor) Titus in 70 AD.

Marble from the Coliseum

Main article: Saint Peter's Square St Peter's Square
There is a widespread assumption that the dome, or cupola, as it presently stands, was designed by Michelangelo, who became chief architect in 1546. In fact, Michelangelo's design called for a spherical dome. At the time of his death (1564), only the drum set, the base on which a dome rests, had been completed. The dome proper was redesigned and vaulted by the architect Giacomo della Porta, with the assistance of Domenico Fontana, who was probably the best engineer of the day. Fontana built the lantern the following year, and the finial was placed in 1593. Many are fascinated by the ability of the artist of who created it.
As built, the double dome is brick, 42.3 meters (138.8 ft) in interior diameter (almost as large as the Pantheon), rising to 120 meters (394 ft) above the floor. In the mid-18th century, cracks appeared in the dome, so four iron chains were installed between the two shells to bind it, like the rings that keep a barrel from bursting. (Visitors who climb the spiral stairs between the dome shells can glimpse them.) The four piers of the crossing that support it are each 18 metres (59 ft) across. It is not simply its vast scale (136.57 m or 448.06 ft from the floor of the church to the top of the added cross) that makes it extraordinary. Della Porta's dome is not a hemisphere, but a paraboloid: it has a vertical thrust, which is made more emphatic by the bold ribbing that springs from the paired Corinthian columns, which appear to be part of the drum, but which stand away from it like buttresses, to absorb the outward thrust of the dome's weight. The grand arched openings just visible in the illustration but normally invisible to viewers below, enable access (but not to the public) all around the base of the drum; they are dwarfed by the monumental scale of their surroundings. Above, the vaulted dome rises to Fontana's two-stage lantern, capped with a spire.
The egg-shaped dome exerts less outward thrust than a lower hemispheric one (such as Mansart's at Les Invalides) would have done. The dome conceived by Donato Bramante at the outset in 1503 was planned to be carried out with a single masonry shell, a plan discovered to be infeasible. Antonio da Sangallo the Younger came up with the double shell, and Michelangelo improved upon it. The piers at the crossing, which were the first masonry to be laid, and which were intended to support the original dome, were a constant concern, too slender in Bramante's plan, they were redesigned several times as the dome plans evolved.
Other domes around the world, built since, are generally compared to this one or contrasted with it.

Dome
Above the main entrance is the inscription,
The façade is 114.69 metres (376.28 ft) wide and 45.55 metres (149.44 ft) high. On top are statues of Christ, John the Baptist, and eleven of the apostles; The statues of St Peter and St Paul are in front of the parish. Two clocks are on either side of the top, the one on the left has been operated electrically since 1931, its oldest bell dating to 1288.
Between the façade and the interior is the portico. Mainly designed by Maderno, it contains an 18th century statue of Charlemagne by Cornacchini to the south, and an equestrian sculpture of Emperor Constantine by Bernini (1670) to the north. The southernmost door, designed by Giacomo Manzù, is called the "Door of the Dead". The door in the center is by Antonio Averulino (1455), and preserved from the previous basilica.
The northernmost door is the "Holy Door" in bronze by Vico Consorti (1950), which is by tradition, only opened for great celebrations such as Jubilee years. Above it are inscriptions, the top reading PAVLVS V PONT MAX ANNO XIII, and the one just above the door reading GREGORIVS XIII PONT MAX. In between are white slabs commemorating the most recent openings.
IOANNES PAVLVS II P.M. PORTAM SANCTAM ANNO IVBILAEI MCMLXXVI A PAVLO PP VI RESERVATAM ET CLAVSAM APERVIT ET CLAVSIT ANNO IVB HVMANE REDEMP MCMLXXXIII – MCMLXXXIV

IOANNES PAVLVS II P.M. ITERVM PORTAM SANCTAM APERVIT ET CLAVSIT ANNO MAGNI IVBILAEI AB INCARNATIONE DOMINI MM-MMI

PAVLVS VI PONT MAX HVIVS PATRIARCALIS VATICANAE BASILICAE PORTAM SANCTAM APERVIT ET CLAVSIT ANNO IVBILAEI MCMLXXV


Interior
Façade
St. Peters, seen from above
High altar
Dome 1
Dome 2
Dome 3
View of the Dome from the Drum
High altar
Bernini's "Cathedra Petri" and "Gloria"
The Basilica of Saint Peter viewed from the Ponte Sant'Angelo
The facade of Saint Peter's Basilica at dusk
..and at dawn
The narthex or entrance hall has three doors
View from the first step beyond the entrance hall
Giovanni Paolo Pannini's painting of the nave of the Basilica of Saint Peter
Bernini's canopy
The confessio.
The tomb of Pope Alexander VII, by Gianlorenzo Bernini
La Pietà sculpted by Michelangelo Buonarroti
Interior view of the sanctuary looking from the dome towards the apse
The view from the top of the dome
Saint Peter's Basilica
Statue of Saint Peter
The interior

Archpriests of Saint Peter's Basilica since 1820