Nagano is the capital and largest city of Nagano Prefecture, located in the Nagano Basin in the central Chūbu region of Japan. Nagano is categorized as a core city of Japan. Nagano City is the highest prefectural capital in Japan, with an altitude of 371.4 meters. The city is surrounded by mountains, the highest of which is Mount Takatsuma, and it is near the confluence of the Chikuma River—the longest and widest river in Japan—and the Sai River.