In support of the first opinion, there is the undoubted fact that the Theodosian Walls, as they approach the Kerko Porta, bend north-eastwards, so that if continued in that direction they would reach the Golden Horn near the Greek Church of St. Demetrius, to the west of Balat Kapoussi. The opinion that the Theodosian Walls were carried to the foot of the western spur of the Sixth Hill rests upon the fact that traces of old fortifications enclosing that spur are still distinctly visible; while the Theodosian Moat is, moreover, continued towards Aivan Serai, until it is stopped by the Wall of Manuel, which runs transversely to it.[454] The fortifications referred to are found mostly to the rear of the Comnenian Wall, but portions of them are seen also to the north of it. One line of the fortifications proceeded from the Kerko Porta along the western flank of the spur, and joined the city walls a little to the south of the “Tower of Isaac Angelus;” another line ran from that gate along the eastern side of the spur to the fountain Tsinar Tchesmè in the quarter of Londja, a short distance to the south-east of the Holy Well which marks the site of the Church of Blachernæ; while a third wall, facing the Golden Horn, defended the northern side of the spur, and abutted against the city walls, very near the southern end of the Wall of Heraclius.[455] Within the acropolis formed by these works of defence, the Palace of Blachernæ and the Palace of the Porphyrogenitus were in due time erected. Both answers to the question before us have much in their favour, and possibly the truth on the subject is to be found in their combination. Their respective values as rival theories will, perhaps, be more easily estimated, if we begin with the consideration of the second answer. [Illustration: Balcony in the Southern Façade of the Palace of the Porphyrogenitus.] That the western spur of the Sixth Hill was a fortified position early in the history of the city can scarcely be disputed. It must have been so, to commence at the lowest date, before the erection of the Wall of the Emperor Manuel in the twelfth century; for it was to get clear of the fortifications on that spur that the Comnenian Wall describes the remarkable detour it makes in proceeding from the court of the Palace of the Porphyrogenitus towards the Golden Horn, running out westwards for a considerable distance before taking a northerly course in the direction of the harbour. Then, there is reason to believe that the spur was fortified as early as the seventh century. This is implied in the accounts we have of the siege of Constantinople by the Avars in 627, when we hear of fortifications, named the Wall of Blachernæ,[456] the Pteron[457] or Proteichisma,[458] outside of which stood the Church of Blachernæ and the Church of St. Nicholas.[459] [Illustration: Archway leading to the Gate of the Xylokerkus (Screen Tower). The Palace of the Porphyrogenitus (From The West).]