, ▁on ▁B uz za ▁Hill ▁and ▁at ▁New ford ▁Down , ▁has ▁led ▁some ▁writers ▁to ▁link ▁them ▁to ▁L yman ’ s ▁proposal . ▁ ▁However , ▁his ▁proposal ▁was ▁never ▁en act ed , ▁and ▁the ▁three ▁to wers ▁have ▁different ▁orig ins . ▁ ▁Harry ' s ▁W alls ▁ ▁Harry ' s ▁W alls ▁are ▁the ▁remains ▁of ▁an ▁un fin ished ▁art illery ▁castle ▁situated ▁on ▁a ▁hill top ▁to ▁the ▁north - east ▁of ▁Hugh ▁Town . ▁It ▁was ▁begun ▁in ▁ 1 5 5 1 ▁as ▁part ▁of ▁a ▁major ▁phase ▁of ▁fort ification ▁on ▁the ▁Is les ▁of ▁Sc illy , ▁undert aken ▁to ▁counter ▁thre ats ▁from ▁the ▁French . ▁ ▁It ▁was ▁left ▁un fin ished ▁because ▁the ▁site ▁was ▁recogn ised ▁to ▁be ▁un su itable . ▁ ▁Gi ant ' s ▁Castle ▁ ▁Gi ant ' s ▁Castle ▁is ▁an ▁Iron ▁Age ▁cl iff ▁castle ▁on ▁the ▁coast al ▁path ▁between ▁the ▁air field ▁and ▁P orth ▁Hel lick ▁Bay . ▁ ▁The ▁G arrison ▁and ▁Star ▁Castle ▁Star ▁Castle ▁is ▁at ▁the ▁centre ▁of ▁a ▁fort ification ▁system ▁around ▁the ▁west ▁side ▁of ▁St ▁Mary ’ s ▁known ▁as ▁the ▁G arrison . ▁The ▁walls ▁of ▁the ▁castle ▁take ▁the ▁shape ▁of ▁an ▁eight - point ed ▁star . ▁It ▁compr ises ▁an ▁outer ▁wall ▁around ▁the ▁out c rop ▁of ▁H ew ▁Hill , ▁protect ing ▁the ▁town ▁and ▁the ▁castle , ▁with ▁strateg ically ▁placed ▁gun ▁batter