First came the fortifications which constituted the Acropolis of Byzantium.[4] They are represented by the walls, partly Byzantine and partly Turkish, which cling to the steep sides of the Seraglio plateau at the eastern extremity of the First Hill, and support the Imperial Museum, the Kiosk of Sultan Abdul Medjid, and the Imperial Kitchens. That the Acropolis occupied this point may be inferred from the natural fitness of the rocky eminence at the head of the promontory to form the kind of stronghold around which ancient cities gathered as their nucleus. And this inference is confirmed by the allusions to the Acropolis in Xenophon’s graphic account of the visit of the Ten Thousand to Byzantium, on their return from Persia. According to the historian, when those troops, after their expulsion from the city, forced their way back through the western gates, Anaxibius, the Spartan commander of the place, found himself obliged to seek refuge in the Acropolis from the fury of the intruders. The soldiers of Xenophon had, however, cut off all access to the fortress from within the city, so that Anaxibius was compelled to reach it by taking a fishing-boat in the harbour, and rowing round the head of the promontory to the side of the city opposite Chalcedon. From that point also he sent to Chalcedon for reinforcements.[5] These movements imply that the Acropolis was near the eastern end of the promontory. In further support of this conclusion, it may be added that during the excavations made in 1871 for the construction of the Roumelian railroad, an ancient wall was unearthed at a short distance south of Seraglio Point. It ran from east to west, and was built of blocks measuring, in some cases, 7 feet in length, 3 feet 9 inches in width, and over 2 feet in thickness.[6] Judging from its position and character, the wall formed part of the fortifications around the Acropolis. The second circuit of walls around Byzantium is that described by the Anonymus of the eleventh century and his follower Codinus.[7] Starting from the Tower of the Acropolis at the apex of the promontory, the wall proceeded along the Golden Horn as far west as the Tower of Eugenius, which must have stood beside the gate of that name—the modern Yali Kiosk Kapoussi.[8] There the wall left the shore and made for the Strategion and the Thermæ of Achilles. The former was a level tract of ground devoted to military exercises—the _Champ de Mars_ of Byzantium—and occupied a portion of the plain at the foot of the Second Hill, between Yali Kiosk Kapoussi and Sirkedji Iskelessi.[9] The Thermæ of Achilles stood near the Strategion; and there also was a gate of the city, known in later days as the Arch of Urbicius. The wall then ascended the slope of the hill to the Chalcoprateia, or Brass Market, which extended from the neighbourhood of the site now occupied by the Sublime Porte to the vicinity of Yeri Batan Serai, the ancient Cisterna Basilica.[10]