Founded in 705 AD, the Koshu Nishiyama Onsen Keiunkan in Kyoto is a hot spring hotel. In 2011, the 37 room hotel was officially recognized by the Guinness World Records as the oldest hotel in the world being continuously operated by 52 generations of the same family! Keiunkan has four open-air baths and two indoor baths for a total of six baths and all of its water is directly sourced from the hot springs! Mt. Fuji and Jigokudani monkey park are located in the same region as the Hotel and a popular sightseeing attraction for many travelers.
Check out the hotel here: http://www.keiunkan.co.jp/en/