Today we visited the Antietam National Battlefield in Sharpsburg, MD. Antietam was the scene of the first major battle of the the U.S. Civil War, occurring on September 17, 1862. It was also the bloodiest day in U.S. history with around 23,000 casualties.
If you are in the area, I highly recommend a trip to Antietam. It is closer to D.C. than Gettysburg, less crowded, and way less commercialized. However, you really ought to checkout Gettysburg too (on a different day), given it's historical significance.
Click the monument picture on the left for a few more shots of the site.