The Old Yaotsu Power Plant (旧八百津発電所) was the first full-scale hydroelectric power plant on the Kiso River. Built by Nagoya Dento (Nagoya Electric Light Company) and completed in 1911 after five years of construction, it powered the region’s industries through the Meiji, Taisho and Showa eras, before being retired in 1974. The brick building houses the generator hall in one wing and the transmission facilities in the other, with the original turbines and generators still sitting in place. It was designated a National Important Cultural Property in 1998, the first Industrial Cultural Treasure of Gifu Prefecture, and recognized as a Heritage of Industrial Modernization in 2007. Strictly speaking, it is not a haikyo anymore: the plant survives as a museum, a rare time capsule of Japan’s early electrification.