Pingyao's walls, built in 1370 from brick and compact earth, have the shape of a turtle. 6km in length, they are punctuated with 72 towers and 3 000 crenellations, in reference to the number of disciples and pupils of Confucius. The walls, which make for a very enjoyable stroll, are little frequented by tourists who prefer to admire the view of the rooftops of the old siheyuan from one of the four watchtowers before walking straight back down.