“Three Centuries at Eastover Farm and the Sippican Mill,” a look at the history of the farm and mill, as well as the generations who have preserved it for more than 300 years, is being held Wednesday at 7 p.m. The free event, sponsored by the Rochester Historical Society, will be at the East Rochester Church and Museum, 355 County Road. The Trustees of Reservations now preserves 75 acres of the property, much of which are rolling fields and abandoned pasture lands. According to the nonprofit conservation agency’s website, Eastover’s 40 acres of hayfields provide an agricultural crop and a habitat for grassland wildlife including bobolinks, meadow voles, and butterflies.