Chiang Mai City Walls. The old town of Chiang Mai was protected by a Long Thick Brick Built City Wall. Amazingly there are a number of sections of the wall still standing along with the old Chiang Mai city gates. The city layout was based on Ancient Military and astrological beliefs. King Mengrai wanted to protect his new city so, he ordered the construction of a perimeter wall and moat; laid in a rectangular shape.