Todaiji temple - The world's largest wooden building hosting the world's largest gilded bronzeBuddha
Traditional towns:
Nakasendo - one of the roads from Old Tokyo (Edo) and Kyoto passes through the Nagano prefecture. Some of the post towns (juku) along this road have been preserved and show the lifestyles of both the commoners and the high ranking officials.
Gassho zukkuri are traditional style houses from the mountain region of Gifu prefecture. A visit to Shirakawago and Takayama are well worth the effort. In Takayama be sure to visit Hida No Sato, an outdoor museum that allows you to walk around the inside of the houses, visit the tea house for free tea and senbei, and enjoy walk around the village.