Several months ago, in Iran, my wife and I saw a lot of these ingenious mechanical air conditioners. Many of them are at least hundreds of years old. Most are square.
But some are octagonal.
The space inside the tower is partitioned vertically into columns. The wind passing around the tower is drawn into the window facing the wind, downwards through a column to the bottom of the tower, up the column on the opposite side, and out the window in the direction of the wind. In the process, the airflow carries moisture out of the tower, lowering the temperature.
It is a wonderful piece of engineering, making use of physics to achieve natural air conditioning without the expense of energy.