A Guide to
​St Peter's Basilica

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The Dome

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Dome

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The majestic dome of St Peter's Basilica, which is 42.3 metres in diameter, was partly conceived by Michelangelo. But when the master died on February 18th 1564 only the drum was complete. The cupola was later constructed by Giacomo della Porta, with the assistance of Domenico Fontana, at the behest of Pope Sixtus V (r. 1585-90). It was raised in just 22 months, thanks to the work of 800 labourers, and completed before the pope's death on August 27th 1590.

Lantern

The lantern was added during the reign of Pope Gregory XIV (r. 1591-92). On November 18th 1593, the large gilded bronze sphere surmounted by the cross, the work of Sebastiano Torrigiani, was placed on the spire of the lantern. Rising to a height of 136 metres, it is the tallest dome in the world. 

Interior of the Dome

The decoration of the interior of the cupola was undertaken by Giuseppe Cesari (1568-1640), better known as the Cavaliere d'Arpino, and carried out with the help of a large team of assistants.

Inscription to Pope Sixtus V

The cupola is made up of sixteen sections, each of which is divided into six parts. At the very top, and closest to God the Father (lantern ceiling), are the heads of the Seraphim. Descending, and growing in size, there is a circle of angels, the heads of the Cherubim, more angels, a series of images of Christ, the Virgin Mary, St John the Baptist, St Paul and the twelve Apostles, while in the lunettes at the base of the cupola are half-length images of bishops and patriarchs.
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At the base of the lantern is a dedicatory inscription to Pope Sixtus V (r. 1585-90): S · PETRI GLORIAE SIXTVS · PP · V · A M · D ·X · C · PONTIF · V · (To the glory of St Peter, Pope Sixtus V, 1590, fifth year of his pontificate). 

​Ringing the base of the cupola, in letters almost 2 m high, is the inscription: TV ES PETRVS ET SVPER HANC PETRAM AEDIFICABO ECCLESIAM MEAM ET TIBI DABO CLAVES REGNI CAELORVM (Thou art Peter, and upon this rock I will build my church. And I will give unto thee the keys of the kingdom of heaven, Matthew 16:18-19, KJV).

Mosaic of St John the Evangelist

The four huge pendentives are decorated with images of the four Evangelists. Under the roundels runs the Latin inscription: HINC VNA FIDES MVNDO REFVLGET HINC SACERDOTI VNITAS EXORITVR (Hence a single faith shines throughout the world. Hence arises the unity of the Priesthood).

A Lion's Head Flanked by Two Bunches of Pears

In addition to the inscription to Sixtus V, there are further references to the pope on the exterior of dome. They take the form of a series of lions' heads flanked by bunches of pears, part of the pope's armorial bearings. (The pope's family name was Peretti-Montalto and pera is the Italian word for pear.)

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