Chinese historical sites (and some city buildings) here in Henan have a tendency to have these sharp warnings NOT to climb the walls.  Given how much looting and destruction they’ve faced with their heritage in the past, it is a pointed (pun intended) reminder that history is to be protected, not stolen or broken.  Also – avoid the Baiju (China’s alcoholic beverage which is as much as 70% alcohol). Getting drunk on that and stupidly climbing the fence is a REALLY BAD idea here!