The walls of Troy VI are the most impressive single piece of architecture surviving on the mound — long stretches of carefully fitted ashlar limestone, two metres thick, originally rising about five metres before the mud-brick superstructure on top. They were built around 1700 BC and stood for several centuries until the city was destroyed (probably by an earthquake) around 1300 BC, after which Troy VIIa rose on the same site.
The technique is called "cyclopean" because the stones are large and roughly squared, fitted closely without mortar in a slightly sloping batter that helped them resist earthquake damage. Walk along the well-preserved southern and eastern stretches and the masonry is visible at almost full original height in places. The walls were considerably extended after the Trojan War period and continued to be visible (and to influence the city plan) right through to Roman times. Information panels along the path explain the construction phases and the dating.