Feast of the Dedication of Saint John Lateran

From the Liturgy of the Hours:
The anniversary of the dedication of the Lateran Basilica, which was erected by the Emperor Constantine, has been observed on this day since the twelfth century. This feast was at first observed only in Rome but later in honor of the basilica, which is called the mother church of Christendom, the celebration was extended to the whole Latin Church. This action was taken as a sign of devotion to and of unity with the Chair of Peter which, as Saint Ignatius of Antioch wrote, "presides over the whole assembly of charity."