The venue of the First Ecumenical Synod in 325 was not in a church, but in the biggest hall of the imperial palace in Nicaea. Emperor Constantine called for this Synod and was present in full regalia during deliberations among the 318 Holy Fathers gathered to restore unity among the Christians of the Roman Empire, divided as it was between the Arians and the Orthodox. During the reign of Justinian part of this palace collapsed and he ordered for its full restoration. By the eighth century, the grand hall of the palace was turned into a church dedicated to the 318 Holy Fathers of the First Ecumenical Synod, otherwise known as the Church of the Holy Fathers.
The first visitor that we have a record of visiting this shrine to the Holy Fathers was the English pilgrim Willibald (c. 727-729) who, after mentioning the Synod of 318 bishops convened by Constantine, goes on, "That church is similar to the one on the Mount of Olives, where the Lord ascended to heaven, and in that church [at Nicaea] were pictures of the bishops who attended the Synod." Willibald had himself visited the Church of the Ascension at Jerusalem and noted the fact that it was unroofed and so let in rainwater. In the middle of it stood some kind of bronze altar containing a candle under a glass cover so it could burn in any weather. Willibald had, therefore, a good mental picture of the Church of the Ascension, which had been more fully described by Arculf (679-688) as a rotunda, unroofed in the middle, surrounded by three vaulted galleries. Whether its central space was completely or only partially open to the sky, the Church of the Ascension would have borne a generic resemblance to a type of building that had a long tradition in Roman architecture, namely the domed rotunda or octagon with a more or less large oculus at the centre. That formula had featured in temples, palaces (e.g. Nero's Golden House) and mausolea, and was later applied to a few martyria of the Holy Land. In the case of the Church of the Ascension a large opening would have been particularly appropriate so as to show visually Christ's elevation to heaven from the spot marked by his footprints. That was not, however, a formula used in Byzantine church architecture. It is not unreasonable to suppose that the shrine visited by Willibald had been converted from the palace hall in which the Synod was believed to have taken place.
In 727, shortly before or after Willibald's visit, Nicaea was besieged by a strong Arab army. This event - the only recorded siege of Nicaea in the course of the centuries-long Arab-Byzantine conflict - is known to us from two accounts in Syriac and two in Greek. Arabic sources are silent, probably because the attack ended in failure. It was at that time that a miracle took place, as recorded by Theophanes in his Chronicle:
"At the summer solstice of the same 10th indiction [June 727] a multitude of Saracens was drawn up against Nicaea in Bithynia: Amr with 15,000 scouts led the van and surrounded the town, which he found unprepared, while Mu'awiya followed with another 85,000 men. After a long siege and a partial destruction of the walls, they did not overpower the town thanks to the acceptable prayers addressed to God by the Holy Fathers who are honored there in a church (wherein their venerable images are set up to this very day and honored by those who believe as they did). A certain Constantine, however, who was the groom of Artabasdos, on seeing an image of the Mother of God that had been set up, picked up a stone and threw it at her. He broke the image and trampled upon it when it had fallen down. He then saw in a vision the Lady standing beside him and saying to him, 'See, what a brave thing you have done to me! Verily, upon your head have you done it.'
The next day, when the Saracens attacked the walls and battle was joined, that wretched man rushed to the wall like the brave soldier he was, and was struck by a stone discharged from a siege engine, and it broke his head and face, a just reward for his impiety. After collecting many captives and much booty the Arabs withdrew. In this manner God showed to the impious one [Leo III] that he had overcome his fellow-countrymen not on account of his piety, as he himself boasted, but for some divine cause and inscrutable judgment, whereby so great an Arab force was driven away from the city of the Holy Fathers thanks to their intercession - on account of their most exact likenesses that are honored therein - and this, too, in reproof and unanswerable condemnation of the tyrant [again Leo III] and in vindication of the true believers. The impious fellow was not only mistaken about the natural reverence due to the revered icons, but also about the intercession of the most holy Mother of God and of the saints. Like his teachers the Arabs, the totally bloody man loathed their remains.
From that time on he impudently harassed the blessed Germanos, Patriarch of Constantinople, blaming all the emperors, bishops and Christian people who had lived before him for having committed idolatry in worshiping the holy and venerable icons, unable as he was to grasp the argument concerning their relative veneration (σχετικής προσκυνήσεως) because of his lack of faith and crass ignorance."
The failed siege of 727 is commemorated by an inscription that is still extant a short distance west of the Istanbul gate on the city side of tower 71 (see photo above). Carved in raised letters and pompously, if somewhat ungrammatically worded, it may be translated as follows:
"At the place where, with divine help, the insolence of the enemy was put to shame, there our Christ-loving emperors Leo and Constantine restored with zeal the city of Nicaea, having erected in demonstration of their deed a trophy of victory by setting up a kentenarìon tower, which Artabasdos, the glorious patrician and curopalates, completed by his toil."
The inscription marks, therefore, the very spot where the Arabs were "put to shame." Not only tower 71, but the whole stretch of wall between towers 70 and 72 was reconstructed at this time out of reused marble blocks and column shafts taken from ancient buildings. That was probably the stretch that was partially destroyed, as Theophanes puts it.
In a Laudation of the 318 Fathers by a certain Gregory, presbyter of the Church of Caesarea in Cappadocia, expressly commissioned by an unnamed bishop of Nicaea, we are informed of the following. At the conclusion of the Synod Constantine offers a banquet and embraces the confessors. As the Fathers are about to depart and offer prayers for the safety of the city that had welcomed them, "it so happened that a fount of oil gushed out of the so-called mesomphalon [circular plaque in the floor] of the eastern entrance, at the very center of the apsis [arch or vault] where the choir of the saints had assembled; which fount, still visible today, demonstrates the efficacy of the prayers offered at the time."
In the same Laudation he records another miracle, due to the Fathers' providence, that happened "in our generation." When the 'Assyrians' were ravaging the Roman Empire, probably the seige of 727, Nicaea was preserved unharmed, "having suffered no loss of men, women or children either by fire or sword" in spite of many enemy attacks conducted both openly and by stealth. Their commander made an attempt against the Church of the Fathers and hastened "to celebrate there the detestable rites of his magic", but was stopped by a nocturnal vision and apparitions by daylight. Indeed, he sought to propitiate God by lighting lamps and barred access to the holy church to his 'Babylonians'. Even prisoners taken by them escaped injury by claiming they were natives of Nicaea. The bodies of the Fathers have remained uncorrupted. The author can testify to this in the case of Leontius, Bishop of Caesarea, his home town. The same applies to Gregory of Armenia, the one who discovered the relics of Ripsime and Gaiane and converted King Tiridates. "Many persons have seen his precious body along with me. It has lost neither its hair nor its fingernails and is suffused with the sweet smell of myrrh".
In 740 a major earthquake struck Nicaea, destroying many church, but the Church of the Holy Fathers survived, but it may not have been in good shape, seeing that the Seventh Ecumenical Synod was not held here, but in the Church of Hagia Sophia. It is often mistaken that the First Ecumenical Synod was held in the Church og Hagia Sophia in Nicaea (Iznik), but it was not.
The images of the Fathers that were seen by Willibald in the 720's were certainly a group representation, hence a historical rather than a devotional picture. There is a possible reference to it in the Admonition of an Old Man Concerning the Holy Icons of c. 750, but the text is incomplete and unclear. Theophanes, as we have seen, refers to it as still extant in c. 813. A few years later (820-828) the Patriarch Nikephoros, who had certainly visited Nicaea, speaks twice of the same composition. The church built in honor of the Fathers, he says, preserves to this day, in addition to other holy representations, the images of the Fathers and of Constantine in brilliant mosaic. The iconoclasts, he claims, tried to remove them, but did not succeed in doing so. It is difficult to imagine that the iconoclasts, who saw themselves as standing in the tradition of Nicaea I, would have wanted to do such a thing.
Both the Church of the Holy Fathers and the Church of Hagia Sophia were destroyed in the earthquake of 1065. It was probably repaired and re-appears later as a monastery. Two intriguing references are, however, worth mentioning. An ecclesiastical synod met at Nicaea in 1232 "in the domed oaton" of what was then the Greek Patriarchate in exile. The name oaton (ovatum, egg-shaped) was also applied to a hall in the Imperial Palace at Constantinople. It was there that both the Sixth Ecumenical Synod (680/81) and the Quinisext (692) assembled. Could the oaton of Nicaea have been the patched up rotunda of Constantine's palace? Two years later (1234) a Latin delegation came to Nicaea and were shown the church in which the First Synod had purportedly met. In it they saw a painting representing that assembly. Was it the mosaic we have discussed or a later substitute for it?
Adapted from here.