The wall is made from tens of millions of standardized red bricks made from the local loess soil and fired in kilns, as opposed to a mixture of earth, brick, wood and stone. These red bricks have given the wall the nickname “Red Snake”.
The length of the wall is not exactly known for its western terminal was flooded by the rising waters of the Caspian Sea, while to the east it runs into the unexplored mountainous landscape of the Elburz Mountains. But the wall was at least 195 kilometers long and 6–10 meters wide. A canal, 5 meters deep, with a continuous gradient ran alongside most of the Wall, conducting water from a reservoir constructed in the highlands down into the Caspian basin. Aside from functioning as a water supply, the canal served as a defensive moat. Along the length of the wall there were built as many as 30 fortresses spaced at intervals of between 10 and 50 km. Researchers estimate that some 30,000 soldiers could have been stationed along its length.
Today, much of the ancient wall lies in ruins, having been eroded over time leaving little more than a scar across the landscape.
A section of the wall.