Ruin of the classical fortification on Külahlıkırtepe (Kadıoğlu, 2021, 153, Figure 54)
In the 20th year of the Peloponnesian War (412 BC), historian and Athenian general Thucydides mentions a wall constructed by the Athenians outside the city of Teos to protect against land attacks. The defence line built of large rectangular blocks cut from local limestone found on Külahlıkır Tepe northeast of the Acropolis differs from the Archaic Wall and Hellenistic Wall in terms of technical workmanship. Unlike the Hellenistic Wall, no clamps or dowels were used to join the blocks, which were roughly carved to appear like bossage work. The top surfaces of the blocks are finely worked without any comb marks. Petrographic and chemical analyses indicate that the blocks used in this defense line were quarried from the middle layers of the limestone quarry, suggesting that this line dates after the Archaic Wall but before the Hellenistic Wall. This defense line is thought to be the first line of defense against enemies coming from the North Harbor or from the land.
Archaeological map of Teos and its surroundings (Kadıoğlu, 2021, 25, Map 4)