The gate was guarded also on the north-west, by the Church of St. Demetrius, another military saint, and was therefore sometimes styled by the Greeks, after the Turkish Conquest, the Gate of St. Demetrius.[886] It was likewise known as the Eastern Gate,[887] owing to its position on the eastern shore of the city. Here, probably, stood one of the gates of old Byzantium; for when the city was occupied by the Greeks under Xenophon, the Spartan admiral, Anaxibius, escaped to the Acropolis by taking boat in the Golden Horn, and rounding the promontory to the side facing Chalcedon.[888] The pier in front of the gate was called the Pier of the Acropolis (ἡ τῆς ἀκροπόλεως σκάλα);[889] and for the convenience of the boatmen and sailors frequenting it, a chapel of St. Nicholas, their patron saint, was attached to the Church of St. Barbara.[890] According to the inscriptions[891] found upon the gate, it was included in the repairs of the seaward walls in the reign of Theophilus. As became its important position, it was a handsome portal, flanked, like the Golden Gate, by two large towers of white marble,[892] and beside it, if not in it, Nicephorus Phocas placed the beautiful gates which he carried away from Tarsus as trophies of his Cilician campaigns.[893] On two occasions it served as a triumphal entrance into the city, John Comnenus using it for that purpose in 1126, to celebrate the capture of Castamon;[894] and Manuel Comnenus in 1168, on his return from the Hungarian War.[895] In 1816 the towers of the gate furnished material for the Marble Kiosk which Sultan Mahmoud IV. erected in the neighbourhood;[896] and in 1871 the gate disappeared during the construction of the Roumelian railway. Proceeding southwards from the Gate of St. Barbara, we reach the entrance known as Deïrmen Kapoussi. It is clearly Byzantine, but its Greek name is lost. Between it and the Gate of St. Barbara must have stood the Mangana (τὰ Μάγγανα),[897] or Arsenal, with its workshops, materials of war, and library of books on military art. Its site is identified by the statement of Nicetas Choniates,[898] that it faced the rocky islet off the shore of Chrysopolis, on which the beacon tower Kiz Kalehssi, or Leander’s Tower, is now built. For, according to that historian, Manuel Comnenus, with the view of closing the Bosporus against naval attack from the south, erected two towers between which he might suspend a chain across the entrance of the straits; one of them, named Damalis and Arcla (Δάμαλις, Ἄρκλα), being on the rock off Chrysopolis,[899] the other, opposite to it, very close to the Monastery of Mangana. The Tower of the Mangana was exceedingly strong, capable of withstanding a siege by the whole city.[900] Hence, in the struggle between Apocaucus and Cantacuzene, the former held it with great determination.