Our Lady of Fourvieres, a sanctuary dating from the time of St Pothinus, erected on the site of a temple of Venus, is a popular place of pilgrimage in the diocese. In 1643 the people of Lyons consecrated themselves to Our Lady of Fourvieres and pledged themselves to a solemn procession on the 8th of December of each year, which still continues to this day. It was in Lyons that sixty Gallic tribes erected the famous altar to Rome and Augustus. It was also the center from which Christianity gravitated throughout Gaul. Brutal persecution arose under Marcus Aurelius. Its victims at Lyons numbered forty-eight, half of them of Greek origin, half Gallo-Roman; among them were St Blandina and St Pothinus, first Bishop of Lyons, sent to Gaul by St Polycarp about the middle of the second century. The letter addressed to the Christians of Asia and Phrygia in the name of the faithful of Vienne and Lyons, and relating the persecution of 177, is considered one of the most extraordinary documents possessed by any literature; it is the baptismal certificate of Christianity in France. The successor of St Pothinus was the illustrious St Irenæus (d. 202).