Most of China's 101 cities classified as famous historical and cultural cities are over 1,000 years old. South of the Yangtze River, Suzhou and Hangzhou, long known as "paradise on earth", are crisscrossed with rivers, lakes, bridges, fields and villages, as beautiful as paintings. Today's well-preserved ancient cities includes that of Pingyao in central Shanxi, but was also the site of the Neolithic era Yangshao and Longshan cultures, 5,000 to 6,000 years ago. Ancient Lijiang in Yunnan is not only the center of Dongba culture of the Nakhi ethnic group but also a meeting place for the cultures of Han, Tibetan and Bai ethnicities. Built in the Song dynasty, this city has many stone bridges, stone memorial arches and dwelling houses, which provide precious materials for architectural history and can be called a "living museum of ancient dwelling houses."