![](https://pbs.twimg.com/media/DZx8FgAX0AAaosl.jpg)
![](https://pbs.twimg.com/media/DZx8GJOW0AArLQ2.jpg)
Once a year, the towers were opened & all the guano was swept out & used as fertiliser.
(goingiran.com/pigeon-tower-y…)
![](https://pbs.twimg.com/media/DZx8G3gWkAIVxSq.jpg)
![](https://pbs.twimg.com/media/DZx8HD8X4AATibb.jpg)
They are mostly found in the dry central Isfahan region of Iran.
(amusingplanet.com/2014/11/the-pi…)
![](https://pbs.twimg.com/media/DZx8H1kWsAAs5s1.jpg)
![](https://pbs.twimg.com/media/DZx8IQXXkAEYF8B.jpg)
The towers range from 10 to 22m in diameter & can be as much as 18m high, housing up to 14,000 pigeons.
![](https://pbs.twimg.com/media/DZx8I-TX4AARdao.jpg)
![](https://pbs.twimg.com/media/DZx8JVAWsAAMO9m.jpg)
The towers were sealed for most of the year to prevent snakes from entering.
(amusingplanet.com/2014/11/the-pi…)
![](https://pbs.twimg.com/media/DZx8J6rW4AAFdGq.jpg)
![](https://pbs.twimg.com/media/DZx8KSmWAAMQlVW.jpg)
![](https://pbs.twimg.com/media/DZx8Ku1W4AENxhG.jpg)
![](https://pbs.twimg.com/media/DZx8LM3X4AAMtyl.jpg)
That means there is no fixed design, & no original creator, but they still form an architecturally unique signature that shows distinct regional variations.
![](https://pbs.twimg.com/media/DZx8LzhXkAE-cJd.jpg)
![](https://pbs.twimg.com/media/DZx8MM6WsAAGIa3.jpg)
I'm modern times, movement to the use of synthetic fertiliser in Iran has caused many of the pigeon towers to fall into disuse & ruin.
(antiquity.ac.uk/projgall/pourj…)
![](https://pbs.twimg.com/media/DZx8NJRW4AAyHPp.jpg)
![](https://pbs.twimg.com/media/DZx8NzPXkAEf8Yv.jpg)
Only a few hundred of the towers are actively maintained, compared to the thousands once in operation.
![](https://pbs.twimg.com/media/DZx8OfRXcAAso05.jpg)
![](https://pbs.twimg.com/media/DZx8O-nX0AARrM5.jpg)
(notechmagazine.com/2016/10/pigeon…)
![](https://pbs.twimg.com/media/DZx8PnZW4AAppuq.jpg)
![](https://pbs.twimg.com/media/DZx8PytX4AAZevg.jpg)
Some of these ceilings reaching up to sky could belong to a mosque or a church.
The design of functional architecture creeps into the sacred!
![](https://pbs.twimg.com/media/DZx8QKTWsAEbWZf.jpg)
![](https://pbs.twimg.com/media/DZx8QkqWkAAwQ2P.jpg)
![](https://pbs.twimg.com/media/DZx8Q7wXUAEihlT.jpg)
![](https://pbs.twimg.com/media/DZx8RekW0AAysX3.jpg)