DEXTER'S GRIST MILL. Sandwich, Massachusetts - Cape Cod 3/25 - Video by: Mark TR Filteau. Cape Cod, Massachusetts. Thomas Dexter began building gristmills on this site in 1637 The mill you see here today started operating in about 1654.The early settlers of Sandwich brought their corn to "The Grist Mill to be ground into meal, their most important food. You will see the old machinery, with its wooden gears in full operation, grinding corn Freshly ground meal from the mill, including recipes used