Uirimji Reservoir (제천 의림지와 제림)

Uirimji is one of the three oldest reservoirs in Korea, built in the 3rd century during the Three Kingdoms period and still in agricultural use today — making it one of the world's oldest functioning irrigation works. The reservoir is ringed by a 1.9-kilometer perimeter walking path planted with old pines ("Jerim") that lean dramatically over the water and turn the basin into a contemplative scene year-round. A traditional pavilion sits on the south shore at the historic intake. Locals walk laps here at all hours, and the basin freezes hard enough for ice fishing in winter. Free entry. Allow ninety minutes for the loop. Pair with the Cheongpung Cable Car for a Jecheon day.