Hotel most overwater bungalows resorts. In 2006, "Guinness World Records" listed the First World Hotel in Genting Highlands, Malaysia, as the world's largest hotel with a total of 6,118 rooms (and which has now expanded to 7,351 rooms). The Izmailovo Hotel in Moscow has the most beds, with 7,500, followed by The Venetian and The Palazzo complex in Las Vegas (7,117 rooms) and MGM Grand Las Vegas complex (6,852 rooms). According to the Guinness Book of World Records, the oldest hotel in operation is the Nisiyama Onsen Keiunkan in Yamanashi, Japan. The hotel, first opened in AD 707 has been operated
Onsen found in some onsens with poor sanitation. Revelations of poor sanitary practices at some onsens have led to improved regulation by hot-spring communities to maintain their reputation. There have been reports of infectious disease found in hot bodies of water worldwide, such as various "Naegleria" species. While studies have found the presence of "Naegleria" in hot spring waters, the worrisome "Naegleria fowleri" amoeba has not been identified. Nevertheless, fewer than five cases have been seen historically in Japan, although not conclusively linked to onsen exposure. Many onsens display notices reminding anyone with open cuts, sores, or lesions not to bathe.