The Old Schwamb Mill is the oldest continuously operating mill site in the United States. There has been a mill operating at this site since c.1650. The current mill is a 19th-century woodworking factory. The mill was built in 1861, and purchased by brothers Charles and Frederick Schwamb in 1864 for the manufacture of picture frames. It remained within the family's ownership and continued to operate, more or less unchanged in both equipment and processes, until 1969. Two wings were added during this time, however: one by 1881, and the other between that date and 1898. The mill still contains operational equipment and four preserved power systems.