in the construction of forts and cities, while fired bricks became popular in the later period. Sometimes one brick was set in the vertical position, with two horizontal rows of bricks laid above and below. The sizes of mud or fired bricks differ, but in general the standard size was 40 × 40 × 10 cm. The fired bricks were made from the local loess soil, and fired in kilns along the line of the wall. This wall starts from the Caspian coast, circles north of Gonbade Kavous (ancient Gorgan, or Jorjan in Arabic), continues towards the northeast, and vanishes in the Pishkamar Mountains. The wall lies slightly to the north of a local river, and features a ditch that conducted water along most of the wall. In 1999 a logistical archaeological survey was conducted regarding the wall due to problems in development projects, especially during construction of the Golestan Dam, which irrigates all the areas covered by the wall. At the point of the connection of the wall and the drainage canal from the dam, architects discovered the remains of the Great Wall of Gorgan. The 40 identified fortresses vary in dimension and shape but the majority are square fortresses, made of the same brickwork as the wall itself and at the same period. Due to many difficulties in development and agricultural projects, archaeologists have been assigned to mark the boundary of the historical find by laying cement blocks. Larger than Hadrian's Wall and the Antonine Wall taken together (two separate structures in Britain that marked the northern limits of the Roman Empire), it has been called the greatest monument of its kind between Europe and China. The wall is second only to the walls that make up the Great Wall of China as the longest defensive wall in existence, and although now in substantial disrepair, it was perhaps even more solidly built than the early forms of the Great Wall. Route The route, from east to west, is represented by the coordinates of the remains of the following forts and other features which lie along the wall. The coordinates and fort numbers, etc. are from Wikimapia: East end of wall West end of wall Dating Dr. Kiani, who led the archaeological team in 1971, believed that the wall was built during the Parthian Empire (247 BC–224 AD), and that it was reconstructed and restored during the Sassanid era