There's enough to hold you for a half a day at DUJIANGYAN (formerly Guanxian ), a large town 60km northwest of Chengdu reached from either Ximen or the north bus stations (¥8). It was here in 256 BC that the provincial governor, Li Bing , set up the Dujiangyan Irrigation Scheme to harness the Min River , a notoriously capricious tributary of the Yangzi. Li designed a three-part engineering project using a central dam and artificial islands to split the Min into an inner flow for irrigation and an outer channel for flood control. A spillway directed and regulated the water, and allowed silt to be dredged, while an opening carved through the hillside controlled the flow of oncoming water. Completed by Li Bing's son, the scheme has been maintained ever since, so that the present system of dams, reservoirs and pumping stations irrigates some 3.2 million hectares.

Dujiangyan's bus station is south of the centre on Yingbin Dadao; turn left up Taiping Jie for a kilometre to a T-intersection, then bear left and follow the road around to Lidui Park (¥5), which encloses the original heart of the project. Lively eave carvings and an ancient stone statue of Li Bing grace Fulong Guan (Subduing Dragon View), a wooden, 1600-year-old temple flanked with die-straight nanmu trees which sits right at the tip of the first channel. The name symbolizes the taming of the river, and it's a good place to see the scheme's layout; for even better views, take the chairlift (¥16) from beside Fulong Guan across the river and up to Erwang Miao (¥15), the Two Kings' Temple. Posthumously dedicated to Li Bing and his son, who are remembered by statues in the two main halls, this is an unspoiled complex built of heavy stone, and holds a wedge of tree trunk said to be four thousand years old. Above is a road - from where you can catch bus #1 back to the bus station - and a disappointingly restored pagoda ; below, steps descend to the plank-and-wire Anlan Cable Bridge (¥3), where you can cross the Min and follow footpaths back to town.

For somewhere to stay in Dujiangyan, try the clean and helpful Jingyuan Binguan (¥75-100), just up from the bus station on Taiping Jie; there are dozens of places to eat along Taiping Jie and around the entrance to Lidui Park. Leaving , buses head back to Chengdu and on to Qingcheng Shan through the day, with at least daily services west to Wolong and Xiaojin, and north to Wenchuan and Songpan.