It was customary at the time for the hermits to wander from place to place. Among the famous hermits who visited Sinai was Julian Sabbas († 363), who left his cell near Osrhoene (Edessa), and, with a few devoted followers, sought the remoteness of Sinai where he remained some time. On reaching the desired height (τὸ ποθούμενον ὄρος), he built a church and set up an altar on the stone on which Moses, prince of prophets, rested. Theodoret (_c._ 450), who related this, stated that the altar remained in his day.[152] Antoninus Martyr (_c._ 530) noted the existence of an oratory above Pharan, with its altar on the stones which supported Moses when he prayed.[153] The plan and ruins of an oratory are figured in the Ordnance Survey (pl. X), which probably mark this spot. Its erection helped to locate the struggle of Moses and the Amalekites in this valley, which, according to other views, took place further south. The hermits at this period occupied caverns and huts, an older man, called _abbas_, _i.e._ father, usually dwelling with a younger disciple. But as time wore on the cells were more and more grouped around a centre where the hermits assembled once a week for religious service. These centres or churches sometimes consisted of a square tower built of stone, its entrance raised above the ground, and in these the hermits sought refuge in times of danger. One such tower or church stood near Raithou, and formed part of the later convent of St. John; another, the Arbaïn, now in ruins, stood in the Wadi Layan, near the grotto of Onophrius; a third was near the Bush, and was included in the present convent. Tradition claimed that the tower near the Bush, was built by Helena, the mother of the emperor Constantine, and was dedicated to the Theotokos in order to commemorate the spot where the Lord appeared to Moses in the Burning Bush.[154] The tower was pointed out to Burckhardt, and was described by him as of older construction than the convent.[155] The pilgrimage of Helena to the East in the year 326 is well authenticated, but there is no contemporary reference to her entering Sinai. If there were, it would be the earliest association of the site of the convent with the coming of Moses. We first hear of bishops established in cities of Sinai in connection with religious discussions and difficulties. At the beginning of the fourth century Arius raised doubts regarding the fundamental truth of the Divine Sonship, and a synod of three hundred and ninety bishops met at Nicæa in the year 325 to discuss the question. Among those who set their signature to the declaration of faith which rejected the claims of Arius was Peter, bishop of Ahila, _i.e._ Aila, a city which, by virtue of its situation was included in the province of Palestine.[156]