This photo was sent in by Bob Martin. Bob was reading David McCullough's book "Truman", and a photo of construction in the White House caught his eye. It was taken during remodeling of the White House in 1950 by photographer Abbie Rowe.
At the back right of the photo, an apparition can be seen standing in the construction works. Compared to the other men in the photo, it's size scale is accurate. And if this were due to some motion or long exposure effect, the rest of the photo should be affected, as well.