But the point of most importance in the whole discussion is the comparative ages of the towers N and S. As a building in existence when Alexius Comnenus occupied the throne of Constantinople, the Tower of Anemas was, at least, seventy years older than the Tower of Isaac Angelus. Hence, if the tower S is the former, it must be older than the tower N, which Dr. Paspates identifies with the Tower of Isaac Angelus. But the evidence which has been submitted goes to prove that the tower S is more recent than the tower N. These towers, therefore, cannot be, respectively, the Tower of Anemas and the Tower of Isaac Angelus. Nothing can prove that the tower S is the Tower of Anemas, until S is shown to be earlier than N, or the identification of the tower N with the Tower of Isaac Angelus is abandoned as erroneous. Dr. Paspates,[536] indeed, assigned the tower S to the reign of Theophilus in the ninth century, on the ground that a block of stone upon which some letters of that emperor’s name are inscribed is built into the tower’s north-western face. But a little attention to the way in which that stone is fitted into the masonry will make it perfectly evident that the stone has not been placed there to bear part of an inscription, but as ordinary material of construction, obtained from some other edifice. Consequently, it throws no light upon the age of the tower. Where, then, was the Tower of Anemas? Perhaps, in our present state of knowledge, no answer which will commend itself as perfectly satisfactory can be given to the question. The simplest solution of the difficult problem is that the tower L, which bears the inscription in honour of Isaac Angelus, is, after all, the tower erected by that emperor, though greatly altered by injuries and repairs; and that the towers N and S together constituted the prison-tower of Anemas, S being a later addition. Others may prefer to hold the view that the tower N is the Tower of Anemas, and the tower S that of Isaac Angelus, pointing in support of this opinion to the cells in the tower N, reached from the stairway by narrow vaulted passages. This would mean, practically, that the Tower of Isaac Angelus was the Tower of Anemas renovated and enlarged. Possibly, others may be disposed, notwithstanding the inscription of Isaac Angelus upon it, to regard the tower L as the Tower of Anemas, and the tower N, with the later addition of S, as that of Isaac Angelus. If none of these views is acceptable, we must fall back upon the opinion which prevailed before Dr. Paspates discovered the chambers adjoining the tower N and S, viz. that the towers N and S together formed the Tower of Isaac Angelus, and that the Tower of Anemas was one of the three towers in the Heraclian Wall. This was the view of the Patriarch Constantius,[537] who writes: “The Tower of Anemas still exists. On its side facing the Holy Well of Blachernæ it has a large window, with a smaller one above.”