Gates of Alexander

The Gates of Alexander was a legendary barrier supposedly built by Dhul-Qarnayn in the Caucasus to keep the uncivilized barbarians of the north (typically associated with Gog and Magog) from invading the land to the south. The gates were a popular subject in medieval travel literature, starting with the Alexander Romance in a version from perhaps the 6th century. The wall has been frequently identified with the Caspian Gates of Derbent, Russia (see below) and with the Pass of Dariel or Darial.

An alternative theory links it to the so-called "Alexander's Wall" (the Great Wall of Gorgan) on the south-eastern shore of the Caspian Sea, 180 km of which is still preserved today, albeit in a very poor state of repair.

In reality both structures were built by the Persian monarchs. Derbent (in Persian دربند Darband, meaning "closed gates"), was established in the end of the 5th or the beginning of the 6th century, when the city was refounded by Kavadh I of the Sassanid dynasty of Persia.

The Great Wall of Gorgan was built during the Parthian dynasty simultaneously with the construction of the Great Wall of China and it was restored during the Sassanid era (3-7th century)