Dujiangyan Irrigation System，is located west of Dujiangyan City，Sichuan Province. Originally it was called Du'an Weir after the name of the ancient Du'an County，where the weir was situated. Since Song and Yuan Dynasties it was given the present name Dujiang Weir，honored as the "Guarding Treasure of Sichuan Province" that is "ingenious of all times".