The Section of the Old City Walls are the remains of a wall that surrounded the colonial city of Macau, in Portuguese Macau, in the 16th and 17th centuries.
The wall's construction is unique because it was built of clay, sand, rice straw, rocks, and oyster shells.
Wikipedia https://en.wikipedia.org/wiki/Walls_of_Macau
Address 9 Calcada De S. Francisco Xavier, Macau, Macau SAR China
Coordinates 22°11'51.832" N 113°32'25.775" E