It is not impossible that these chambers were store-rooms or barracks,[527] and that through the loopholes in the wall BB the palace was defended as, previously, through the openings in AA. Communication between the three stories must have been maintained by means of wooden stairs or ladders. In the north-eastern wall of C’—the chamber which gave access from the court of the Palace of Blachernæ at _v_ to the second story of the tower N—there was an archway, now filled up, opening upon the level of the highest series of chambers C. When the archway was closed, communication was held through a breach at _h_. Possibly the same series of chambers was entered from the north-eastern end of the upper gallery in AA. Contrary to what might be supposed, there was no access to the two upper series of chambers from the stairway-turret. Whether the lowest series could be reached by a door at the foot of the stairway cannot be ascertained, on account of the earth in which the lower portion of the stairway lies buried. But it is extremely improbable that such was the case, for the stairway-turret belongs, we have seen, to a later age than the chambers in the body of the adjoining wall. With these points made clear, we are in a position to consider how far the identification of the towers N and S, respectively, with the historical towers of Isaac Angelus and Anemas can be established. According to Nicetas Choniates, the Tower of Isaac Angelus stood at the Palace of Blachernæ, and was built by that emperor to buttress and to defend the palace, and to form, at the same time, a residence for his personal use.[528] It was constructed with materials taken from ruined churches on the neighbouring seashore, and from various public buildings in the city, ruthlessly torn down for the purpose.[529] This account makes it certain, in the first place, that the Tower of Isaac Angelus was one of the three towers which flank the portion of the city walls now under consideration, the portion which forms the north-western side of the enclosure around the Palace of Blachernæ; for these towers, and they only, at once defended and supported the terrace upon which that palace stood. This being the case, it is natural to suppose that the Tower of Isaac Angelus is the tower which bears the inscription in his honour.[530] But this opinion is attended with difficulties. For the tower in question does not differ in any marked manner from an ordinary tower in the fortifications of the city. It is not specially fitted for a residence, nor does it possess features which render it worthy to have a place in history among the notable buildings erected by a sovereign. Furthermore, it is not constructed, to any striking degree, with materials drawn from other edifices.