Again, the Palace of the Porphyrogenitus was occupied by John Cantacuzene, in 1347, while negotiating with the Dowager-Empress Anna of Savoy to be acknowledged the colleague of her son, John Palæologus.[436] Upon taking possession of that residence he issued strict injunctions that no attack should be made upon the palace in which the empress and her son were then living. But the followers of Cantacuzene, hearing that Anna hesitated to come to terms, disobeyed his orders and seized the fort at Blachernæ, named the Castelion, which guarded that palace.[437] Evidently the Palace of Blachernæ and the Palace of the Porphyrogenitus stood near each other. Seven years later, John Palæologus himself, upon his capture of the city, made the Palace of the Porphyrogenitus his headquarters while arranging for the abdication of Cantacuzene.[438] And from the narrative of the events on that occasion it is, again, manifest that the Palace of the Porphyrogenitus was in the neighbourhood of the Castelion and the Palace of Blachernæ. By this identification, a flood of light is shed upon the incidents of Byzantine history to which allusion has just been made. The palace, an oblong building in three stories, stands between the two parallel walls which descend from the Porta Xylokerkou for a short distance, towards the Golden Horn. Its long sides, facing respectively north and south, are transverse to the walls, while its short western and eastern sides rest, at the level of the second story, upon the summit of the walls. Its roof and two upper floors have disappeared, and nothing remains but an empty shell. The northern façade was supported by pillars and piers, and its whole surface was decorated with beautiful and varied patterns in mosaic, formed of small pieces of brick and stone. The numerous windows of the building were framed in marble, and, with the graceful balconies on the east and south, looked out upon the superb views which the lofty position of the palace commanded. The western façade, being the most exposed to hostile missiles, was screened by a large tower built on the west side of the Porta Xylokerkou, to the injury, however, of the gate, which was thus partially blocked up. A transverse wall erected at some distance to the north made the area between the two walls, upon which the palace rests, a spacious court, communicating by a gate at its north-eastern corner with the city, while a gate in the western wall led to the parateichion.[439] The latter entrance is, probably, the one known as the Postern of the Porphyrogenitus, by which forty-two partisans of John Cantacuzene made good their escape from the city in 1341.[440] [Illustration: Monogram Of The Palæologi.]