...just to add....i would be keeping the think 7ft wooden fence up and simply adding in front of it cages of rocks for my 3ft width x 7ft high x 7ft in length wall.

In front of that i would put a medium height tree . The space is very narrow / by the side of our house hence im limited. But its in my mind to do it now...just would love any advice / other solutions / a safety aspect...i mean a 7ft rock wall...in cages...im not expert...but wont fall down?