The second photo shows the little alcove between the viewing windows. You get down on your hands and knees (appropriate for where you are), crawl into the alcove, and then insert your arm into the little hole and feel the top of Calvary. After 2,000 years of people rubbing the top of the mountain, it is very, very smooth. You can also feel a square hole chisled into the mountain, which I estimated to be about 9 inches square. The hole is deep; I couldn't reach the bottom. This is the center cross hole of the 3 at the top of the mountain; traditionally Jesus was crucified on the center cross.