If you're in Boston this weekend, you should visit the Boston Public Library's Civil War exhibits. While several exhibits will be open only during weekday business hours, the Torn in Two: The 150th Anniversary of the Civil War exhibit is fantastic. There's also a really good exhibit of Homer Winslow Civil War era prints, largely done for newspapers (9am - 5pm, Mon., Wed., and Fri.; 9am - 7pm Tues. and Thurs.).
Both are superb.