The Mill Cove Complex is a group of prehistoric archaeological sites located in Duval County, Florida built by people of the St. Johns culture approximately 900 to 1250 CE. The site encompasses 2 sand mounds, Grant Mound (8DU14) and the contemporaneous Shields Mound (8DU12) located 750 metres (0.47 mi) away, and an area in between the two which is full of St. Johns culture midden deposits.