Chengtoushan Cultural Site in the west of Lixian County is the oldest and best preserved site of a city with the richest cultural relics in China. There are sites of the city moat and an altar. Some plots of rice field under the city wall, dating back to 6,500 years ago, are the earliest and best-preserved ones so far found in China. They prove that the Yangtze River Valley is also a cradle of the Chinese civilization.