We managed to be among the last twenty or thirty people allowed to climb Waynu Picchu, that peak on the left.  The Incas had built a precarious staircase and a small fortress on top.  It took us about an hour and a half to pick our way up the stairs; the Inca runners did it in ten minutes.  The clouds had rolled back in, so we were mercifully unable to see much of the valley floor hundreds of feet below.