The house at 429 Prospect Avenue was built by Hamilton Richardson in 1871. The Italianate mansion is constructed from cream city brick, sitting on over an acre and a half of land in the center of the Prospect Hill historic neighborhood.
Richardson was Janesville's most successful businessman of the late 19th century. Originally from Genesee County New York, Hamilton Richardson (1820-1906) came to Janesville in 1846 from Milwaukee and Racine. He had invested in the city's downtown commercial district during a very successful economic boom in 1856. Richardson was considered a man of high integrity and a devoted public servant, taking terms as Janesville's Postmaster, Rock County Commissioner, State Senator and State Representative for southern Wisconsin.
In 1858 Richardson married Caroline Pease, the daughter of prominent Janesville attorney John Pease. They had six children. Their eldest son, Victor Richardson married Tallman cousin Mary Dimock in 1885 at the William Morrison Tallman House, the most elegant Victorian wedding in Janesville's history. Victor's sister Sarah Richardson served as a bridesmaid.
Members of the Richardson family occupied the home until 1934. The house was then sold and divided into apartments. Restoration of the home started in 1978. Through comparison with historic photographs in the Rock County Historical Society Archives, missing architectural features were replaced and existing features were restored to their original beauty. The Richardson Home was placed on the National Register of Historic Places in 1992.