35 - Oak Hill Sanatorium

E. Main and Country Club Drive, Lake Geneva, WI 53147

Oak Wood Sanatorium was opened in 1885 but had fallen into ruins by the time Gary Gygax and his friends went exploring the place late at night. Located atop Catholic Hill, the five story brick asylum, in addition to various halls and rooms throughout, had a series of tunnels and chambers beneath. According to Gary, these passages provided his first experience with dungeon exploration, facing real life dangers of groping through dark tunnels. In one instance Gary stopped in the pitch darkness, deciding to turn around. Later when the explored the place during the day, he discovered he had just narrowly avoided falling through a jagged hole in the floor, dropping down a long way! The building was razed in 1959.