So a common site around the Middle East are pigeon towers. Every country will have a different style that is common to their region.
What is a pigeon tower and why are they needed you ask?
Now that modern technology provides for synthetic fertilizers, shipping/trading also allows for importation of enriched soils, and I have even signs warning that sprinkler water is not potable as it is gray water, the use of Pigeon Towers is not necessary. Though they are still used as a cultural or traditional reminder of years gone by.