Crail

A bartizan (an alteration of bratticing), also called a guerite or échauguette, or spelled bartisan, is an overhanging, wall-mounted turret projecting from the walls of late medieval and early-modern fortifications from the early 14th century up to the 18th century. Most frequently found at corners, they protected a warder and enabled him to see his surroundings. Bartizans generally are furnished with oillets or arrow slits. The turret was usually supported by stepped masonry corbels and could be round, polygonal or square. Quoted from Wikipedia