Pigeon Houses of Iran
Fascinating!
There were thousands of these buildings during the Safavid dynasty, about the 16th century CE. They were built to collect the droppings as fertilizer for melon and cucumber fields… However, in modern times chemically produced fertilizers have drastically reduced the viability of the bird guano industry and as a result not many of these structures have survived to the present day. The droppings were also used in the process of tanning leather.
