The Harbour Fortifications guarded the northern side of the city, from the Acropolis (Seraglio Point) to the terminus of the land walls at Blachernæ, and, excepting a small portion, consisted of a single wall, flanked, according to Bondelmontius, by a hundred and ten towers.[656] To accommodate the commerce and traffic of the city, the wall was built, for the most part, at a short distance from the water; but the strip of ground thus left without the fortifications was even narrower in ancient times than it is at present, much of the land outside the wall having been made by recent deposits of earth and rubbish. This explains how the Venetian fleet, in 1203 and 1204, was able to approach so near the ramparts that troops standing on the flying bridges attached to the ships’ yards came to close quarters with the defenders on the walls. Indeed, in one case, at least, such a bridge spanned the distance between ship and tower, and permitted the assailants to cross over and seize the latter.[657] At the actual distance, however, of the wall from the water, such a feat would be impossible, except in the vicinity of the Seraglio Point, which was not the quarter attacked by the Venetians. Gates. At a short distance to the east of the Xylo Porta a breach in the wall marks the site of a gateway named by the Turks Kutchuk Aivan Serai Kapoussi—“the Small Gate of Aivan Serai.”[658] It stands at the head of a short street leading southwards to the site of the famous Church of the Theotokos of Blachernaæ, while to the north is the landing of Aivan Serai Iskelessi, which accommodates this quarter of the city. Here, probably, was the Porta Kiliomenè (Κοιλιωμένη Πόρτα),[659] at which the emperors—as late, at least, as the beginning of the thirteenth century—landed and were received by the Senate, when proceeding by water to visit the Church or the Palace of Blachernæ. Nowhere else could one disembark so near that sanctuary and that palace. The landing-stage before the gate must, therefore, have been the Imperial Pier (Ἀποβάθρα τοῦ βασιλέως) mentioned by Nicetas Choniates. Some authorities, it is true, place that landing at Balat Kapoussi. But it could not have been there when Nicetas Choniates wrote; for that historian[660] refers to the Apobathra of the Emperor to indicate the position of the Wall of Leo, which was attacked by the Latins in 1203. Now, points which could thus serve to identify each other must have been in close proximity. But Balat Kapoussi and the Wall of Leo are too far apart for the former to indicate the site of the latter. On the other hand, the Wall of Leo and Aivan Serai Iskelessi are very near each other.