But when the Emperor Constantine had by the Sacrament of Baptism received health both of body and soul, then first in a law by him published was it allowed to the Christians throughout the whole world to build Churches, to the which holy building he exhorted them by his example as well as by his decree. He dedicated his own Lateran Palace a Church to the Saviour, and built hard by it a Cathedral in the name of St. John the Baptist, upon the place where he had been baptized by holy Sylvester, and cleansed from his leprosy. This Cathedral was hallowed by the said Pope upon the 9th day of November. It is this consecration, the memory of which is still celebrated upon this day, the first whereon the public consecration of a Church ever took place in Rome, and the image of the Saviour was seen by the Roman people painted upon a wall.
The Blessed Sylvester afterwards decreed, when he was consecrating the Altar of the Prince of the Apostles, that altars were thenceforward to be made of stone only, but notwithstanding this the Lateran Basilica hath the altar made of wood. This is not surprising. From St. Peter to Sylvester the Popes had not been able, by reason of persecutions, to abide fixedly in one place, and they celebrated the Holy Liturgy in cellars, in burying-places, in the houses of godly persons, or wherever need drave them, upon a wooden altar made like an empty box. When peace was given to the Church, holy Sylvester took this box, and to do honour to the Prince of the Apostles, who is said to have offered sacrifice thereon, and to the other Popes who thereon had been used to execute the mystery even unto that time, set it in the first Church, even the Lateran, and ordained that no one but the Bishop of Rome should celebrate the Liturgy thereon for all time coming. The original Lateran Basilica, cast down and destroyed by fires, pillage, and earthquakes, and renewed by the constant care of the Popes, was at last rebuilt afresh, and solemnly consecrated by Pope Benedict XIII, a Friar Preacher, upon the 28th day of April, in the year 1726, the memory of which Festival he ordained to be kept upon this day. In the year 1884 Leo XIII took in hand a work which had received the sanction of his predecessor Pius IX. The great sanctuary, the walls of which were giving way with age, was lengthened and widened, a task of immense labour. The ancient mosaic had been renewed previously in several places; it was now restored according to the original design, and transferred to the new apse, the embellishment of which was carried out with great magnificence. The transept was redecorated, and its ceiling and woodwork repaired. A sacristy, a residence for the canons, and a portico connecting with the Baptistery of Constantine, were added to the existing buildings.