Hundreds of pigeon towers or dovecotes, dating largely to the Safavid reign, dot the fields in the vicinity of Isfahan. Distinct examples of secular architecture in Iran, these structures played an important role, much alike the subterranean canal system (qanats), in sustaining the hinterland that made possible an urban center at Isfahan. The turrets built with the purpose of collecting pigeon dung were a significant source of local revenue and were frequently decorated with white plaster and crenellations.