The L-Shaped Georgian Revival Style one-story building, which now houses the Mason County Historical Society Museum, was constructed in 1914 and is the only example of this style of building in the City. The building was designed by Frederick Heath, which became one of Washington State’s most prominent architects in the early part of the century. The building was built in memory of Sol G. Simpson, founder of Simpson Timber Company and was given to the people of Shelton from Mary Garrard Simpson (Nickname Tollie) who was the widow of Sol Simpson. The building was placed on the National Register of Historic Places in 1984 and on the Shelton Historic Register in April of 1995.