This fifth and final photo from the 1951 catalog is one of the most interesting.  It is taken in the central portion of the layout to the left of the large lake.  The Santa Fe streamliner is actually coming out of a curve to the left and proceeding up a grade.  Apparently, Gilbert saw this magnificent vista as a flat space on which a loop of trestles could be erected, because that appears to be just what they did some time after this photo was taken.  Compare this photo with the view on the 1957 and 1958 catalog covers.  The semaphore was left in its original position which makes it easier to see that this is the same area.   Compare also, the shape of the highest mountain in the photo.  By 1958, the aircraft beacon, which is absent in the 1957 photo, appears to have been replaced by a whistling billboard.