The correct name of the village is “Stare Osowo,” but for unknown reasons the reverse form has become more popular. It used to be simply Osowo or Ossowo, which was first mentioned in the 14th century. The Osowo mansion, which still exists today, dates from the early 18th century. It constitutes an eclectic, one-story, brick building, covered with a gabled roof. The entrance is preceded by a wooden veranda, above which is a storied roof overhang, topped with a triangular roof. The mansion is surrounded by a 2-hectare park from the 19th century. In 1754 Leon Antoni Raczynski, castellan of Santock, royal lieutenant general, acquired the Osowo estate, which remained in the hands of the Raczynski family (owners of Obrzycko) until the end of World War II. After the war, the former estate was nationalized and parceled out by the State Treasury.
