Two of the three mounds ,just outside of the main camp defensive ditch,show up quite nicely in this shot.I was standing on top of the third mound,taking the shot.It is generally accepted that this camp and the three mounds were Roman Practice Works.It is thought that the three mounds supported ballista(giant crossbows).The mounds are about 10 feet at the highest point.If that's what they were for,I hope the Roman soldiers had some form of crane to lift the devices up onto the top.see http://www.roman-britain.org/places/burnswark.htm