Successive plans Pope Julius's scheme for the grandest building in Christendom was the subject of a competition for which a number of entries remain intact in the
Uffizi Gallery, Florence. It was the design of
Donato Bramante that was selected, and for which the foundation stone was laid in 1506. This plan was in the form of an enormous
Greek cross with a dome inspired by that of the huge circular Roman temple, the
Pantheon. When Pope Julius died in 1513, Bramante was replaced with
Giuliano da Sangallo and
Fra Giocondo, who both died in 1515 (Bramante himself having died the previous year).
Raphael was confirmed as the architect of St. Peter's on 1 August 1514. The main change in his plan is the nave of five bays, with a row of complex apsidal chapels off the aisles on either side. 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. In 1520 Raphael also died, aged 37, and his successor
Baldassare Peruzzi maintained changes that Raphael had proposed to the internal arrangement of the three main apses, but otherwise reverted to the Greek cross plan and other features of Bramante. This plan did not go ahead because of various difficulties of both Church and state. In 1527 Rome was sacked and plundered by
Emperor Charles V. Peruzzi died in 1536 without his plan being realized. Sangallo's main practical contribution was to strengthen Bramante's piers, which had begun to crack. He is to be regarded as the principal designer of a large part of the building as it stands today, and as having brought the construction to a point where it could be carried through. 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. Michelangelo wrote, "I undertake this only for the love of God and in honour of the Apostle". He insisted that he should be given a free hand to achieve the ultimate aim by whatever means he saw fit. File:SaintPierre.svg|Bramante's plan|alt=This is plan 1 of 3. The plan is based on a square, superimposed on a cross with arms of equal length. The cross makes the main sections of the church building: nave and chancel crossed by the transepts, with a circular dome over the crossing. There are four smaller domes, one in each corner of the square. The arms of the cross project beyond the square. File:L’Architecture de la Renaissance - Fig. 8.PNG|Raphael's plan|alt= Plan 2. This plan has an extended nave with two aisles on either side of it. The main spaces of the church form a Latin cross. File:L’Architecture de la Renaissance - Fig. 13.PNG|Michelangelo's plan|alt= Plan 3. This plan shows a return to the form of plan 1 but with all the various parts made bolder. File:
Michelangelo's contribution Michelangelo took over a building site at which four piers, enormous beyond any constructed since ancient Roman times, were rising behind the remaining nave of the old basilica. He also inherited the numerous schemes designed and redesigned by some of the greatest architectural and engineering minds of the 16th century. There were certain common elements in these schemes. They all called for a dome to equal that engineered by
Brunelleschi a century earlier and which has since dominated the skyline of Renaissance Florence, and they all called for a strongly symmetrical plan of either
Greek Cross form, like the iconic
St. Mark's Basilica in Venice, or of a
Latin Cross with the transepts of identical form to the chancel, as at
Florence Cathedral. Even though the work had progressed only a little in 40 years, Michelangelo did not simply dismiss the ideas of the previous architects. He drew on them in developing a grand vision. Above all, Michelangelo recognized the essential quality of Bramante's original design. 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." As it stands today, St. Peter's has been extended with a nave by
Carlo Maderno. It is the
chancel end (the ecclesiastical "Eastern end") with its huge centrally placed dome that is the work of Michelangelo. Because of its location within the
Vatican State and because the projection of the nave screens the dome from sight when the building is approached from the square in front of it, the work of Michelangelo is best appreciated from a distance. What becomes apparent is that the architect has greatly reduced the clearly defined geometric forms of Bramante's plan of a square with square projections, and also of Raphael's plan of a square with semi-circular projections. Michelangelo has blurred the definition of the geometry by making the external masonry of massive proportions and filling in every corner with a small
vestry or stairwell. The effect created is of a continuous wall surface that is folded or fractured at different angles, but lacks the right angles which usually define change of direction at the corners of a building. This exterior is surrounded by a
giant order of Corinthian pilasters all set at slightly different angles to each other, in keeping with the ever-changing angles of the wall's surface. Above them, the huge cornice ripples in a continuous band, giving the appearance of keeping the whole building in a state of compression.
Dome: successive and final designs The dome of St. Peter's rises to a total height of from the floor of the basilica to the top of the external cross. It is the
tallest dome in the world. Its internal diameter is , slightly smaller than two of the three other huge domes that preceded it, those of the
Pantheon of
Ancient Rome, , and
Florence Cathedral of the
Early Renaissance, . It has a greater diameter by approximately than Constantinople's
Hagia Sophia church, completed in 537. It was to the domes of the Pantheon and Florence
duomo that the architects of St. Peter's looked for solutions as to how to go about building what was conceived, from the outset, as the greatest dome of
Christendom.
Bramante and Sangallo, 1506 and 1513 depicting Bramante's design, including two of the four flanking smaller domes The dome of the Pantheon stands on a circular wall with no entrances or windows except a single door. The whole building is as high as it is wide. Its dome is constructed in a single shell of
concrete, made light by the inclusion of a large amount of the volcanic stones tuff and pumice. The inner surface of the dome is deeply
coffered which has the effect of creating both vertical and horizontal ribs while lightening the overall load. At the summit is an ocular opening across which provides light to the interior. Sangallo's plan (1513), of which a large wooden model still exists, looks to both these predecessors. He realized the value of both the coffering at the Pantheon and the outer stone ribs at Florence Cathedral. He strengthened and extended the peristyle of Bramante into a series of arched and ordered openings around the base, with a second such arcade set back in a tier above the first. In his hands, the rather delicate form of the lantern, based closely on that in Florence, became a massive structure, surrounded by a projecting base, a
peristyle and surmounted by a spire of conic form. Most of the other changes were of a cosmetic nature, such as the adding of lion's masks over the swags on the drum in honour of Pope Sixtus and adding a circlet of
finials around the spire at the top of the lantern, as proposed by Sangallo. Stefan du Pérac's engraving (1569) shows a hemispherical dome, but this was perhaps an inaccuracy of the engraver. The profile of the wooden model is more ovoid than that of the engravings, but less so than the finished product. It has been suggested that Michelangelo on his death bed reverted to the more pointed shape. 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. The rare survival of this example is probably due to its fragmentary state and the fact that detailed mathematical calculations had been made over the top of the drawing.
Addition of nave and facade On 18 February 1606, under
Pope Paul V, the dismantling of the remaining parts of the Constantinian basilica began. Another influence on the thinking of both the Fabbrica and the Curia was a certain guilt at the demolition of the ancient building. The ground on which it and its various associated chapels,
vestries and
sacristies had stood for so long was hallowed. The only solution was to build a nave that encompassed the whole space. In 1607 a committee of ten architects was called together, and a decision was made to extend Michelangelo's building into a nave. Maderno's plans for both the nave and the
facade were accepted. The building of the nave began on 7 May 1607, and proceeded at a great rate, with an army of 700 labourers being employed. The following year, the façade was begun, in December 1614 the final touches were added to the
stucco decoration of the vault and early in 1615 the partition wall between the two sections was pulled down. All the rubble was carted away, and the nave was ready for use by
Palm Sunday.
Maderno's facade The facade designed by Maderno, is wide and high and is built of
travertine stone, with a giant order of Corinthian columns and a central pediment rising in front of a tall
attic surmounted by thirteen statues:
Christ flanked by eleven of the
Apostles (except Saint Peter, whose statue is left of the stairs) and
John the Baptist. The inscription below the
cornice on the tall
frieze reads: (Paul V (Camillo Borghese), born in Rome but of a Sienese family, liked to emphasize his "Romanness".) The facade is often cited as the least satisfactory part of the design of St. Peter's. The reasons for this, according to James Lees-Milne, are that it was not given enough consideration by the Pope and committee because of the desire to get the building completed quickly, coupled with the fact that Maderno was hesitant to deviate from the pattern set by Michelangelo at the other end of the building. Lees-Milne describes the problems of the façade as being too broad for its height, too cramped in its details and too heavy in the
attic story. The breadth is caused by modifying the plan to have towers on either side. These towers were never executed above the line of the facade because it was discovered that the ground was not sufficiently stable to bear the weight. One effect of the facade and lengthened nave is to screen the view of the dome, so that the building, from the front, has no vertical feature, except from a distance. and somewhat enlarged to fit the new space.
Maderno's nave , 1731|alt=A painting of the interior of the vast building with arcades, and a coffered ceiling To the single bay of Michelangelo's Greek Cross, Maderno added a further three bays. He made the dimensions slightly different from Michelangelo's bay, thus defining where the two architectural works meet. Maderno also tilted the axis of the nave slightly. This was not by accident, as suggested by his critics. An ancient
Egyptian obelisk had been erected in the square outside, but had not been quite aligned with Michelangelo's building, so Maderno compensated, in order that it should, at least, align with the Basilica's façade. The nave has huge paired
pilasters, in keeping with Michelangelo's work. The size of the interior is so "stupendously large" that it is hard to get a sense of scale within the building. The four
cherubs who flutter against the first piers of the nave, carrying between them two
holy water basins, appear of quite normal cherubic size, until approached. Then it becomes apparent that each one is over 2 metres high and that real children cannot reach the basins unless they scramble up the marble draperies. The aisles each have two smaller
chapels and a larger rectangular chapel, the Chapel of the Sacrament and the Choir Chapel. These are lavishly decorated with marble, stucco,
gilt,
sculpture and
mosaic. Remarkably, all of the large altarpieces, with the exception of the Holy Trinity by Pietro da Cortona in the Blessed Sacrament Chapel, have been reproduced in mosaic. Two precious paintings from the old basilica, Our Lady of Perpetual Help and Our Lady of the Column are still being used as altarpieces. 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. Its marble steps are remnants of the old basilica and around its
balustrade are 95 bronze lamps.
Influence on church architecture The design of St. Peter's Basilica, and in particular its dome, has greatly influenced
church architecture in
Western Christendom. Within Rome, the huge domed church of
Sant'Andrea della Valle was designed by Giacomo della Porta before the completion of St Peter's Basilica, and subsequently worked on by Carlo Maderno. This was followed by the domes of
San Carlo ai Catinari,
Sant'Agnese in Agone, and many others.
Christopher Wren's dome at
St Paul's Cathedral (
London, England), the domes of
Karlskirche (
Vienna, Austria),
St. Nicholas Church (
Prague, Czech Republic), and the
Pantheon (
Paris, France) all pay
homage to St Peter's Basilica. The 19th and early-20th-century architectural revivals brought about the building of a great number of churches that imitate elements of St Peter's to a greater or lesser degree, including
St. Mary of the Angels in Chicago,
St. Josaphat's Basilica in
Milwaukee,
Immaculate Heart of Mary in Pittsburgh and
Mary, Queen of the World Cathedral in
Montreal, which replicates many aspects of St Peter's on a smaller scale.
Postmodernism has seen free adaptations of St Peter's in the
Basilica of Our Lady of Licheń, and the
Basilica of Our Lady of Peace of Yamoussoukro. ==Bernini's furnishings==