The church is mentioned in history only by Phrantzes,[325] who informs us that when the Patriarch Gennadius transferred the patriarchal seat to the monastery and church of the Pammakaristos, certain nuns previously accommodated in that House were removed to the neighbouring monastery of S. John Baptist in Trullo. Phrantzes explains the designation of the church, 'in Trullo,' as derived from a palace named Trullus which once stood in the vicinity to the north of the Pammakaristos. It was the palace, adds the historian,[326] in which the Council of Constantinople, known as the Concilium Quinisextum ([Greek: Penthektê]), or the second Concilium Trullanum, assembled in 692, in the reign of Justinian II. But the palace Trullus, in which the first Concilium Trullanum met in 680, was one of the group of buildings forming the Great Palace[327] beside the Hippodrome, and there the second Concilium Trullanum also held its meetings.[328] Phrantzes is therefore mistaken in associating the Council of 692 with a palace in the vicinity of the Pammakaristos and Achmed Pasha Mesjedi. But his mistake on that particular point does not preclude the existence of a palace named Trullus in the neighbourhood of the Pammakaristos. In fact, the existence of such a palace in that district is the only possible explanation of the attachment of the style 'in Trullo' to a church on the site of Achmed Pasha Mesjedi. Nor is it strange to find a name pertaining primarily to a building in the Great Palace transferred to a similar building situated elsewhere. The imperial residence at the Hebdomon, for example, was named Magnaura after one of the halls in the Great Palace.[329] There was an Oaton or Trullus in the palace of Blachernae,[330] and in the palace at Nicaea.[331] Consequently, a palace known as the Oaton or the Trullus might also be situated near the Pammakaristos, to command the fine view from that point of the city. Mordtmann,[332] indeed, maintains that the building to which Phrantzes refers was the palace at Bogdan Serai, the subsequent residence of the Moldavian hospodar in Turkish days, and that the church of S. John in Trullo was not Achmed Pasha Mesjedi, but the church of S. John in Petra (Kesmé Kaya) beside that palace. This opinion, however, is at variance with the statements of Phrantzes and Gerlach. Furthermore, the designation 'in Petra' was so distinctive a mark of the church of S. John near Kesmé Kaya, that the church could scarcely have been recognised under another style. [Illustration: PLATE LV. S. JOHN IN TRULLO, FROM THE SOUTH-WEST.] [Illustration: BALABAN MESJEDI (page 265). INTERIOR VIEW. _To face page 202._] [Illustration: FIG. 68.] _Architectural Features_