Nagano's main draw is Zenkō-ji, and you could spend an entire morning exploring the temple grounds and the Okaidan tunnel beneath the main hall. The Nagano Prefectural Art Museum in adjacent Jōyama Park makes a good companion to the temple visit.
Outside the city centre, Togakushi Shrine is the most rewarding half-day excursion — the cedar-lined approach to the upper shrine is genuinely impressive. The former castle town of Matsushiro rewards those interested in samurai-era Japan, and the nearby Matsushiro Underground Imperial Headquarters is a sobering piece of wartime history. The M-Wave Olympic Arena and surrounding sports park offer a look at the enduring Olympic legacy from 1998.