[3] Designed principally by Donato Bramante, Michelangelo, and Carlo Maderno, with piazza and fittings by Gian Lorenzo Bernini, St. Peter's is one of the most renowned works of Italian Renaissance architecture[4] and is the largest church in the world by interior measure.

The façade of the basilica, with a giant order of columns, stretches across the end of the square and is approached by steps on which stand two 5.55-metre (18.2 ft) statues of the first-century apostles to Rome, Saints Peter and Paul.

Although the New Testament does not mention St. Peter's martyrdom in Rome, tradition, based on the writings of the Fathers of the Church,[clarification needed] holds that his tomb is below the baldachin and the altar of the Basilica in the "Confession".

[16] As one of the constituent structures of the historically and architecturally significant Vatican City, St. Peter's Basilica was inscribed as a UNESCO World Heritage Site in 1984 under criteria (i), (ii), (iv), and (vi).

(John 1:42, and see Matthew 16:18) Catholic tradition holds that Peter, after a ministry of thirty-four years, travelled to Rome and met his martyrdom there along with Paul on 13 October 64 AD during the reign of the Roman Emperor Nero.

[citation needed] In 1939, in the reign of Pope Pius XII, 10 years of archaeological research began under the crypt of the basilica in an area inaccessible since the ninth century.

[28] It was of typical basilical form, a wide nave and two aisles on each side and an apsidal end, with the addition of a transept or bema, giving the building the shape of a tau cross.

Raphael's plan for the chancel and transepts made the squareness of the exterior walls more definite by reducing the size of the towers, and the semi-circular apses more clearly defined by encircling each with an ambulatory.

[9] At this point Antonio da Sangallo the Younger submitted a plan which combines features of Peruzzi, Raphael and Bramante in its design and extends the building into a short nave with a wide façade and portico of dynamic projection.

He did not take on the job with pleasure; it was forced upon him by Pope Paul, frustrated at the death of his chosen candidate, Giulio Romano and the refusal of Jacopo Sansovino to leave Venice.

He reverted to the Greek Cross and, as Helen Gardner expresses it: "Without destroying the centralising features of Bramante's plan, Michelangelo, with a few strokes of the pen converted its snowflake complexity into massive, cohesive unity.

While its appearance, with the exception of the details of the lantern, is entirely Gothic, its engineering was highly innovative, and the product of a mind that had studied the huge vaults and remaining dome of Ancient Rome.

The encircling peristyle of Bramante and the arcade of Sangallo are reduced to 16 pairs of Corinthian columns, each of 15 metres (49 ft) high which stand proud of the building, connected by an arch.

Following his death, the work continued under his assistant Jacopo Barozzi da Vignola with Giorgio Vasari appointed by Pope Pius V as a watchdog to make sure that Michelangelo's plans were carried out exactly.

However, Lees-Milne cites Giacomo della Porta as taking full responsibility for the change and as indicating to Pope Sixtus that Michelangelo was lacking in the scientific understanding of which he himself was capable.

Gardner also comments, "The sculpturing of architecture [by Michelangelo] ... here extends itself up from the ground through the attic stories and moves on into the drum and dome, the whole building being pulled together into a unity from base to summit.

"[42] It is this sense of the building being sculptured, unified and "pulled together" by the encircling band of the deep cornice that led Eneide Mignacca to conclude that the ovoid profile, seen now in the end product, was an essential part of Michelangelo's first (and last) concept.

In one sense, Michelangelo's dome may appear to look backward to the Gothic profile of Florence Cathedral and ignore the Classicism of the Renaissance, but on the other hand, perhaps more than any other building of the 16th century, it prefigures the architecture of the Baroque.

[citation needed] Around the inside of the dome is written, in letters 1.4 metres (4.6 ft) high: TV ES PETRVS ET SVPER HANC PETRAM AEDIFICABO ECCLESIAM MEAM ET TIBI DABO CLAVES REGNI CAELORVM("... you are Peter, and on this rock I will build my church. ...

[note 7] The inscription below the cornice on the 1 metre (3.3 ft) tall frieze reads: IN HONOREM PRINCIPIS APOST PAVLVS V BVRGHESIVS ROMANVS PONT MAX AN MDCXII PONT VII(In honour of the Prince of Apostles, Paul V Borghese, a Roman, Supreme Pontiff, in the year 1612, the seventh of his pontificate)(Paul V (Camillo Borghese), born in Rome but of a Sienese family, liked to emphasize his "Romanness".)

Maderno's last work at St. Peter's was to design a crypt-like space or "Confessio" under the dome, where the cardinals and other privileged persons could descend in order to be nearer to the burial place of the apostle.

Bernini's works at St. Peter's include the baldachin (baldaquin, from Italian: baldacchino), the Chapel of the Sacrament, the plan for the niches and loggias in the piers of the dome and the chair of St.

[25][42] Bernini's first work at St. Peter's was to design the baldacchino, a pavilion-like structure 28.74 metres (94.3 ft) tall and claimed to be the largest piece of bronze in the world, which stands beneath the dome and above the altar.

Its design is based on the ciborium, of which there are many in the churches of Rome, serving to create a sort of holy space above and around the table on which the Sacrament is laid for the Eucharist and emphasizing the significance of this ritual.

In this case, the draped canopy is of bronze, and all the details, including the olive leaves, bees, and the portrait heads of Urban's niece in childbirth and her newborn son, are picked out in gold leaf.

[25][42] As part of the scheme for the central space of the church, Bernini had the huge piers, begun by Bramante and completed by Michelangelo, hollowed out into niches, and had staircases made inside them, leading to four balconies.

As the chair itself was fast deteriorating and was no longer serviceable, Pope Alexander VII determined to enshrine it in suitable splendor as the object upon which the line of successors to Peter was based.

[54] Its removal to its present location by order of Pope Sixtus V and engineered by Domenico Fontana on 28 September 1586, was an operation fraught with difficulties and nearly ending in disaster when the ropes holding the obelisk began to smoke from the friction.

Nowadays a long wide street, the Via della Conciliazione, built by Mussolini after the conclusion of the Lateran Treaties, leads from the River Tiber to the piazza and gives distant views of St. Peter's as the visitor approaches, with the basilica acting as a terminating vista.

Also buried here are Maria Clementina Sobieska, wife of James Francis Edward Stuart, Queen Christina of Sweden, who abdicated her throne in order to convert to Catholicism, and Countess Matilda of Tuscany, supporter of the Papacy during the Investiture Controversy.