Artifact processing -- Lost Towns and Smithsonian Environmental Research Center will hold an open laboratory day from 9 a.m. to 2 p.m. Saturday at Historic London Towne, 839 Londontowne Road, Edgewater. Participants will see how artifacts are processed after a dig and research their relevance in history. Free. 301-238-2737 or 410-222-7440, ext. 3269.