Basilica of Saint Peter

3d model and reconstruction

Basilica of Saint Peter

There is abundant documentation regarding the origin and development of the first basilica whose construction was ordered by Emperor Constantine on the tomb of the apostle Peter. There are actually issues of a historical-archaeological nature, and of course also religious questions, involved which are still being studied in depth. In this case, more than ever, historical, religious events and town planning changes have been so closely connected that they cannot be separated and studied individual.

It all began with the construction of the Circus of Caligula in the Ager Vaticanus. As is well known, according to the Christian tradition, this was the site of Peter’s martyrdom, and the adjacent necropolis is where he was buried.

Around the middle of the 2nd century AD, a niche was built on the tomb which was known as GaiusTrophy, a monument mentioned by the historian Eusebius, built on Peter’s tomb to celebrate his triumph through martyrdom.

During the age of Caracalla in the circus area, now abandoned, a circular mausoleum was erected, initially called Rotonda di S. Andrea, which later became the church of S. Maria della Febbre. After this mausoleum was completed at the end of the 4th century, therefore later than Constantine’s basilica, a second one was built known as Rotonda di S. Petronilla.

The appearance of the original Basilica of St. Peter reconstructed here is totally ‘virtual’, because we know from written sources and images that it was extended and restyled several times over the centuries from the 4th to the 16th century, when it was demolished as replaced by the current Basilica designed by Michelangelo.

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Short history of

Basilica of Saint Peter

After his martyrdom the Apostle Peter was entombed in the necropolis on the Vatican hill. The Emperor Constantine had a majestic basilica built on the site of the tomb in the 4th century. The basilica was demolished through the course of the Renaissance, to be replaced by the present-day structure.

The exact date when work began on Constantine’s basilica is uncertain, but it is believed to be between 319 and 324. The main parts of the building were completed in 337, the year of the Emperor’s death.

The construction of the basilica required an enormous effort, and numerous technical and legal problems had to be overcome. This was particularly true for the placement of the presbytery directly above the tomb, since the necropolis had to be buried and it was protected by very strict Roman laws. Furthermore, the street plan had to be redesigned, enormous amounts of earth had to be moved, and a supporting structure of 240 X 90 meters had to be built for the base of the basilica and portico.

Almost all that remains today of Constantine’s original building are parts of the foundation. However, on the basis of these vestiges of the foundation and thanks to historical records, it is possible to reconstruct an image of the original basilica.

The Basilica was about 90 meters long and 63 wide. It had five naves separated by rows of 22 columns; a transept closed at either end by a rectilinear exedra which was more than 90 meters long and extended beyond the perimeter; and an apse on the west end. The central nave was higher than the others and illuminated by eleven windows. The transept was lower than the central nave and separated from it by a triumphal arch. The apse contained five windows.

The focal point of the composition was the monument Constantine had erected above Peter’s tomb. It was a marble shrine surrounded by a rail situated on the central axis of the apse. A baldachin supported by four spiral columns with carvings of vines stood over the shrine.

The entire Basilica was beautifully decorated, but little is known of the exact details of the decor. Gilded beams lined the ceiling, and the apse was decorated with gold leaf.

A monumental four-bayed portico rose in front of the façade. However, Constantine may have only completed the western portion. A cantharus or fountain was located in the center of the arcade. It was covered by a bronze baldachin supported by eight columns. The famous bronze “Pigna” or pine cone, which may have been taken from the Mausoleum of Hadrian and now gives name to its new location in the courtyard of the Vatican Palaces, was later added.