Where is the oldest surviving windmill?

The windmills at Nashtifan are located in northeastern Iran, near the border with Afghanistan. They are made of clay, straw, and wood, and they use strong seasonal winds to grind grain. Their design is very different from the later European windmill, using vertical sails rather than horizontal blades. Some of the structures are believed to be many hundreds of years old, with origins often linked to the early Islamic period or earlier traditions. They remain an important example of early renewable energy technology.