This ashlar mill is a fine illustration of Croatian building traditions imported by immigrants who settled in Lewistown. These Old World artisans accomplished all phases of the masonry work themselves: extracting the stone from Big Spring Quarry, then rough cutting, transporting, shaping, and finally laying each finished piece in place. Simple arched windows, single-piece downsloped windowsills, and walls of graduated coursed cut stone are crafted with the hands of a skilled master. Although two carefully constructed new wings have expanded the mill for residential use, the original building well represents the skills and talents of immigrant artisans who provided a vital community service and greatly enriched the local landscape. Lewistown received electric service in1893, but within a decade the demand for more power had increased with the population. Big Spring Creek was an ideal source for hydroelectric power. In 1903, the Citizen’s Electric Company built this main powerhouse, which produced 450 kilowatts of electricity for the city of Lewistown. The Upper Spring Creek Power Plant, in operation until 1928, extends over a deep eddy that was once the outlet for the water that drove the water wheel. Power generating equipment occupied the main floor, while the upper level served as living quarters for the operators.