Patterson's Archeological District is a 512-acre (2.07 km2) archaeological site near Wallville in Calvert County, Maryland at the mouth of St. Leonard's Creek, the largest tributary of the tidal portions of the Patuxent River. It contains a representative sample of a range of archeological sites characteristic of both upland and lowland utilization of the Chesapeake Bay tidewater region during the prehistoric and historic periods. The property also contains a range of historic sites.[2]