The foundations of the church were laid in 527, the year of Justinian's accession,[83] and its erection must have been completed before 536, since it is mentioned in the proceedings of the Synod held at Constantinople in that year.[84] According to the Anonymus, indeed, the church and the neighbouring church of SS. Peter and Paul were founded after the massacre in the Hippodrome which suppressed the Nika Riot. But the Anonymus is not a reliable historian.[85] The church did not stand alone. Beside it and united with it, Justinian built also a church dedicated to the Apostles Peter and Paul,[86] so that the two buildings formed a double sanctuary, having a common court and a continuous narthex. They were equal in size and in the richness of the materials employed in their construction, and together formed one of the chief ornaments of the palace and the city. There was, however, one striking difference between them; SS. Sergius and Bacchus was a domical church, while SS. Peter and Paul was a basilica. Styles of ecclesiastical architecture destined soon to blend together in the grandeur and beauty of S. Sophia were here seen converging towards the point of their union, like two streams about to mingle their waters in a common tide. A similar combination of these styles occurs at Kalat-Semân in the church of S. Symeon Stylites, erected towards the end of the fifth century, where four basilicas forming the arms of a cross are built on four sides of an octagonal court.[87] The saints to whom the church was dedicated were brother officers in the Roman army, who suffered death in the reign of Maximianus,[88] and Justinian's particular veneration for them was due, it is said, to their interposition in his behalf at a critical moment in his career. Having been implicated, along with his uncle, afterwards Justin I., in a plot against the Emperor Anastasius, he lay under sentence of death for high treason; but on the eve of his execution, a formidable figure, as some authorities maintain,[89] or as others affirm, the saints Sergius and Bacchus, appeared to the sovereign in a vision and commanded him to spare the conspirators. Thus Justinian lived to reach the throne, and when the full significance of his preservation from death became clear in the lustre of the imperial diadem, he made his deliverers the object of his devout regard. Indeed, in his devotion to them he erected other sanctuaries to their honour also in other places of the Empire.[90] Still this church, founded early in his reign, situated beside his residence while heir-apparent, and at the gates of the Great Palace, and withal a gem of art, must be considered as Justinian's special thankoffering for his crown. With the church of SS. Sergius and Bacchus was associated a large monastery known, after the locality in which it stood, as the monastery of Hormisdas, [Greek: en tois Hormisdou]. It was richly endowed by Justinian.[91] NOTE