I'm almost positive that's the Shirley House in that photo. The Shirley House is the ONLY wartime structure that remains in the park....Okay, I'm POSITIVE that this is the Shirley House. You can still see the remains of the Union approach trench running through the front yard.....and I'm 100 percent sure that Grant never made his H.Q. there...Grant's H.Q. was far to the rear of the lines. If you pull a map of the VNMP you can see where he had his tent in relation to where the Shirley House was located within earshot of the 3rd LA Redan.