On the summer solstice, I went to the Pantheon to await for high noon. I was curious whether the occulus was positioned such that the shaft of light would hit anything. At noon, according to my watch, the shaft of light shone toward the left of the entrance a few degrees. It didn't seem to hit anything in particular. Then I realized I was on daylight savings time. Damn! High noon was actually an hour back! I actually was there at 11 and at that point, the shaft of light was centered on one of the circular patches of stone right at the entrance. I haven't studied the geometries of the building and don't know if it was just a coincidence or not.