Gunther founded the Pioneer Flour Mills in Gillespie County 1851, but after battling poor weather conditions, he decided to relocate his headquarters to San Antonio 1959. In 1960, after building constructing his new mill, he built his home, which is in the King William Historic District, for himself and his wife, Henrietta Dorothea Pape. The Hilmer couple raised seven children in the home.
The home and business has remained in the Guenther family. In 1902, Hilmar's youngest son, Erhard, took on the presidency of Pioneer Flour Mills. He remodeled the home as it appears today, which features a restaurant, store, and museum. The site is listed on the National Register of Historic Places.