I've been real close to there way before the place was built up (just the large building and the conference center, essentially - no big blue spy building etc on the east side yet) - it's at the top of the hill on the west side of the circle (inside the circle). Just a few graves, I believe.
I think this
http://maps.google.com/?ie=UTF8&ll=38.876773,-77.464107&spn=0.000948,0.001287&t=h&z=20 is where it is (center of image).
If you zoom out of this image just a bit there are some interesting linear tree features - don't believe those are natural.