St Peter's Dome
The great dome soars above the altar and the baldacchino, sumptuously embellished with mosaic and stucco ornaments. It is supported by four structural piers with a perimeter of 71 m. and a height of 120 m. from the ground to the roof of the lantern.
The giant letters on a gold background, from St. Veronica to St. Helen, say "Hinc una fides mundo refulgent" (From here a single faith shines throughout the world); and from St. Longinus to St. Andrew: "Hinc sacerdotii unitas exoritur" (From here is born the unity of the priesthood).
In the four spandrels which link the square piers and the circular drum, the four Evangelists are portrayed in medallions with a diameter of 8.5 m.: Matthew with the ox, Mark with the lion, Luke with the angel and John with the eagle.
Around the base of the drum we can read the solemn words from Matthew's Gospel with which Jesus invests Peter with supreme authority. The text reads: "Tu es Petrus et super hanc petram aedificabo ecclesiam mean et tibi dabo claves regni caelorum" ("You are 'Rock' and on this rock I will build my Church, to you I will give the keys of the kingdom of heaven." Mt 16:18).
The gigantic black letters (2 m. high) of this text on a gold background are lit by the light from 16 large windows, typical of Michelangeolo's style, which punctuate the drum.
Above the windows, the dome is divided into sixteen ribs and as many segments, decorated by majestic figures on six ascending concentric levels.
Starting at the bottom the figures portray: 1. busts of the 16 popes buried in the basilica; 2. majestic figures of Christ, the Virgin Mary, St. Joseph, St. John the Baptist and various Apostles; 3. in the rectangular frames, angels bearing the instruments of Jesus' Passion; 4. the faces of cherubim and seraphim in circular medallions; 5. angels, the custodians of St. Peter's tomb 6. additional faces of winged angels.
Michelangelo's dome was only completed to the base when he died.
It was later finished by Porta in 1590
