ST. PETER'S BASILICA

The architectural history of the basilica of St. Peter falls into four main phases: (1) the small memorial set up to mark the Apostle's grave after his martyrdom under Nero (54–68); (2) the great basilica, Old St. Peter's, initiated by Constantine c. 324 and apparently completed by his son Constantius c. 354; (3) the transitional stage, 1506 to 1546, when construction of the new basilica was in a state of flux; and (4) the present building, begun by Michelangelo in the 16th century and completed by Bernini in the late 17th century.

Old St. Peter's. Recent excavations under the basilica have shown that both the Old and the New St. Peter's were centered with great care on a particular grave, although this involved very great technical difficulties. This is presumably the "Trophy" of St. Peter mentioned c. 200 by Gaius; certainly it was believed to be the tomb of Peter by Emperor Constantine (d. 337), under whom the first great basilica was begun. Old St. Peter's, with the Lateran, was one of the first great churches erected for the newly liberated Christians; its architectural features, still preserved in essentials in the Lateran, were fundamental for future church building. Old St. Peter's consisted of an enormous nave and four aisles for the congregation, joined to the confessio, the tomb of the Martyr, which was set at the junction of nave, transepts, and presbytery. The plan drawn by Alpharanus (engraved 1590), together with several drawings and paintings, gives a good idea of the appearance of Old St. Peter's.

During the papacy of Nicholas V (1447–55) it became evident that the building, then more than 1,000 years old, would have to be replaced, Nicholas and his architectural adviser L. B. Alberti apparently began fresh foundations for a choir at the southwest angle, under the direction of Bernardo Rossellino. It is not known how much progress was made, since construction was discontinued soon afterward; but a serious start had been made, judging from Bramante's early designs, which take account of this work.

New St. Peter's. The history of New St. Peter's began soon after the election of Julius II (1503) and before the laying of the foundation stone on April 18, 1506. Julius seems to have decided very early in his pontificate that a real start had to be made on a new building and that he had an adequate architect in Bramante. Perhaps the lack of an architect of Bramante's ambition and experience was responsible for the long delay between Nicholas V and Julius II. The early stages of the planning are very obscure, since no definitive program seems to have been prepared and the medal struck in 1506 to commemorate the laying of the foundation stone seems to represent a Bramante project rather than a specific program. Only one drawing by Bramante himself can be attached to this first project—a large plan on parchment, which may represent half of a symmetrical Greek-cross plan or may be

no more than a design for transepts and choir, to be added to the existing nave. It appears that Bramante experimented for many years with different designs, some in the form of a Greek cross, others closer to the traditional Latin cross of Old St. Peter's. The principal idea was to replan the new building around the tomb, which ipso facto ruled out plans that could not be fitted to the site. There is a large collection of drawings in the Uffizi, Florence, of projects for the new building, but most of them seem to be no more than design exercises by Bramante's pupils and assistants. From these drawings, the medal of 1506, and a group of small centrally planned churches (all built after c. 1508), one may deduce that Bramante's principal project was for a large Greek-cross building with apsidal projections on each side and crowned with an enormous dome, imitating the Pantheon. There is serious doubt whether such a dome would have stood on the four piers that were the basis of the plan. One of these piers was established in 1506 and another was begun before Bramante's death, so that the existing basilica was conditioned by the space between these two piers and the great arch that joins them and, hence, the space of the crossing and the dome over it. This, however, was practically all that Bramante contributed to the present building. After the death of Julius II in 1513, followed by that of Bramante in 1514, comparatively little was done, although the superintending architects were Raphael and Peruzzi, both of whom had worked with Bramante. All building was brought to a stop by the sack of Rome in 1527, and for many years the basilica looked like one of the ruins of Rome, as may be seen from drawings made in the 1530s.

A fresh start was made when Antonio da Sangallo the Younger was called in; he modified the plan considerably. He prepared an elaborate model (1539–46), with many variations from the original designs. The first great change was to abandon the central plan in favor of a long nave, better suited for large crowds. Bramante himself had experimented with a long-nave plan, and Sangallo's model was an awkward compromise consisting of a centrally planned shape, based on one of Bramante's designs, linked by a huge bridge to an elaborate nave with two great towers and a Benediction Loggia in the façade. Sangallo, who was an experienced engineer, also tackled the problem of the dome, redesigning it to spread the weight more effectively and, at the same time, greatly enlarging the supporting piers. Nevertheless, his design was ugly; Sangallo was totally unable to cope with the problems

of colossal scale. He died in 1546, before much work had been done on the actual building.

Design of Michelangelo. Sangallo was succeeded by michelangelo, who at once redesigned the whole building, claiming that he was returning to the basic principles laid down by Bramante—at the same time making caustic remarks on Sangallo's work. Michelangelo's appointment began on Jan. 1, 1547, by which date he had already prepared a rough model; at his death on Feb. 18, 1564, more work had been accomplished than under all his predecessors. Michelangelo's design returned to a central plan with a great dome over it; but unlike Bramante's central plan, one side was emphasized as the entrance side and marked by a portico. Engravings made shortly after Michelangelo's death give a good idea of his plan, which differs from the executed building in the dome, nave, and entrance.

The existing dome, built between 1585 and 1590 by Giacomo della Porta and Domenico Fontana, was probably given its present pointed shape because this helped to spread the load, while the hemispherical dome shown in the engravings after Michelangelo might have proved impractical. The other major difference between the existing building and Michelangelo's project was the reversion once more to a Latin-cross plan. There seems no doubt that Michelangelo, following Bramante, preferred the Greek-cross shape as more symmetrical and more suited to the character of the church. Nevertheless, the Constantinian church had been basilican in plan with an enormous nave, and practical considerations determined the rejection of the Greek-cross in favor of a longer nave. This was achieved very skillfully by Carlo Maderno, who added a long nave to Michelangelo's entrance façade. By this means he also secured large chapels at each side, usable as sacristies until the present sacristy was built in the 18th century. The change from Greek-to Latin-cross involved considerable problems with the façade, since the dome was no longer clearly visible from the front, and the arms of the transepts projected rather awkwardly until they were masked by extending the façade at each side. Maderno's façade is treated like Michelangelo's designs for secular palaces, so that the forms themselves are Michelangelesque, although there is a curiously secular flavor about the façade as a whole. The Benediction Loggia was placed by Maderno over the main door. The two ends were to have had towers added, which would have been a reversion to the original Bramante plan; but when they were begun in 1637, under bernini, the foundations proved inadequate and they had to be demolished.

The piazza outside the church was very successfully incorporated into the design by Bernini when he added an enormous Doric colonnade with semicircular ends, so that the whole of the piazza together with the façade forms a single architectural unit. Originally the colonnade was closed off by a block at the end of the present Via della Conciliazione, so that the visitor saw nothing until he entered the piazza, when the whole design became visible at once. This effect of surprise was ruined by Mussolini, who demolished the central block to give a "vista" from the river bank.

The interior is almost entirely 17th century, although the painting of the dome and the rich mosaics were begun about 1590. Bernini's work was completed by the enormous bronze baldacchino of 1633, followed, as viewed down the nave, by the equally enormous Cathedra Petri, completed in 1666. The whole interior decoration is thus of baroque design. However, the mosaic of "Peter's Barque," originally designed by Giotto, and the bronze doors by Filarete have survived from Old St. Peter's.

See Also: vatican

Bibliography: No full modern bibliography has been published; two most useful works on the whole history of the building are s. schÜller-piroli, 2000 Jahre Sankt Peter (Olten, Switz.1950) and c. galassi paluzzi, San Pietro in Vaticano, 3 v. (Le Chiese di Roma illustrate; Rome 1965); both have extensive literary references. For the problem of the Apostle's tomb there are, in English, e. kirschbaum, Tombs of St. Peter and St. Paul, tr. j. murray (New York 1959) and j. m. toynbee and j. w. perkins, The Shrine of St. Peter (New York 1956). For Old St. Peter's the principal authority is t. alfarano, De Basilicae Vaticanae antiquissima et nova structura, ed. m. cerrati (Studie Testi 26;1914). Many of the drawings and plans for New St. Peter's are reproduced in p. letarouilly, Le Vatican et la Basilique de S. Pierre, 2 v. (Paris 1882; repr. London 1953). The principal sources are still h. von geymÜller, ed., Die ursprünglichen Entwürfe für Sanct Peter in Rom, 2 v. (Vienna 1875–80) and d. frey, Bramantes S. Peter: Entwurf und seine Apokryphen (Vienna 1915).

[p. murray]