Great Wall of Gorgan

The Great Wall of Gorgan runs across the plain of Golestan from near the Caspian shore in the west to the mountains in the east, a distance of about 195 kilometres. Built of fired red brick, it was one of the longest defensive walls of the ancient world, longer than Hadrian's Wall and the Antonine Wall in Britain put together. Local people have long called it Qizil Alan, “the red snake”, after the line of red brick rubble that winds across the fields, and in older tradition it was known as Alexander's Barrier, Sadd-e Eskandar.

For a long time no one knew who had built it or when. Excavations by a joint Iranian and British team, led by Jebrael Nokandeh, Hamid Omrani Rekavandi and Eberhard Sauer, have since dated it to the Sasanian era, most likely the fifth or sixth century CE. It guarded the fertile Gorgan plain against peoples of the steppe to the north, such as the Hephthalites, who were a serious threat to the Sasanian empire in those centuries.

The wall was more than a barrier. Along its length the archaeologists identified more than thirty forts, spaced at regular intervals, and a canal ran alongside it, both supplying water to the brick kilns that made its materials and adding a further obstacle. Behind it lay large military camps. The scale implies a garrison of many thousands of soldiers and a state capable of organising labour and supplies on an enormous scale.

Today much of the wall is a low mound, ploughed over in places and crossed by roads and fields, but its line can still be traced for long stretches. The town of Gonbad-e Kavus, with its famous tower, lies just south of it.