Of the basilicas which existed before the time of Justinian, there are two impressive examples remaining. The first is the church of S. John Baptist, once attached to the monastery called the Studium. It was originally built in 463, and was attached to the monastery founded by one of the early emigrants from the old Rome, Studius. This monastery became the most important centre of the Akoimetai, the "sleepless ones," an order which kept up perpetual intercession for the sins of the world, and whose importance from the fifth century to the time of the Latin Conquest was very great.[51] It was in this church that many of the icons were preserved during the first fury of iconoclasm: in the monastery, Isaac Comnenus and Michael VII. assumed the monastic habit. The church has undergone several restorations, but is now in a ruinous state. It was turned into a mosque under Bayezid II.--it is called Mir Achor Djami--but its structural arrangements have not been altered. It is a basilica with two aisles and apse, narthex and atrium. On each side the aisles are divided from the nave by seven marble pillars, the capitals Corinthian, the work below Byzantine. The design on the capitals is that of the double acanthus, "one leaf lying over and within another." Outside in the atrium the columns are Corinthian, and so also below in the great crypt or cistern. The door of the narthex is inserted between the two columns. Of the many memorials that the church once contained only one may now be seen. In a wall marking a small enclosure behind the apse, at the north-east, is a tombstone upside down on which may be traced the Greek inscription to the memory of Dionysios, a Russian monk, who fell asleep on September 6, 1387. [Illustration: COURTYARD OF THE CHURCH OF THE STUDIUM] Beautiful in its ruin, with the creepers hiding many of the great gaps in the Western entrance, the church of S. John Baptist does not differ essentially from the common Western type of basilica. The galleries (now without floors) mark, it has been said, the advent of organised monasticism earlier than in the West; but there is, save for some of the work on the pillars, nothing of an especially Byzantine style about the church. It seems certain to perish in a few years if nothing is done. Meanwhile it should be visited by every student of history or art.