▁city ▁have ▁supplied ▁some ▁details ▁about ▁how ▁they ▁may ▁have ▁looked , ▁while ▁the ▁lower ▁areas ▁of ▁the ▁Roman ▁Bath s ▁reve al ▁significant ▁remains ▁from ▁the ▁Roman ▁period . ▁ ▁The ▁Bath s ▁were ▁built ▁around ▁hot ▁spr ings , ▁the ▁only ▁ones ▁naturally ▁occurr ing ▁in ▁the ▁United ▁Kingdom . ▁Arch ae ological ▁evidence ▁suggests ▁that ▁the ▁main ▁spring ▁in ▁its ▁natural ▁state ▁was ▁treated ▁as ▁a ▁shr ine ▁by ▁the ▁Cel ts . ▁During ▁the ▁early ▁Roman ▁occupation ▁of ▁Britain , ▁in ▁the ▁ 6 0 s ▁or ▁ 7 0 s ▁AD , ▁engine ers ▁drove ▁o ak ▁p iles ▁into ▁the ▁mud ▁to ▁provide ▁a ▁stable ▁foundation ▁and ▁surrounded ▁the ▁spring ▁with ▁an ▁irregular ▁stone ▁chamber ▁l ined ▁with ▁lead . ▁These ▁still ▁surv ive . ▁At ▁this ▁early ▁stage ▁the ▁spring ▁was ▁an ▁open ▁pool ▁in ▁the ▁corner ▁of ▁the ▁temple ▁prec inct . ▁It ▁fed ▁a ▁bath ing ▁complex ▁on ▁its ▁south ▁side ▁within ▁a ▁bar rel - v ault ed ▁building . ▁The ▁complex ▁was ▁gradually ▁built ▁up ▁over ▁the ▁next ▁ 3 0 0   year s . ▁All ▁the ▁stone work ▁above ▁the ▁level ▁of ▁the ▁bath s ▁is ▁from ▁more ▁recent ▁periods ▁including ▁the ▁ 1 2 th ▁century , ▁when ▁John ▁of ▁T ours ▁built ▁a ▁cur ative ▁bath ▁over ▁the ▁King ' s ▁Spring ▁res er voir , ▁and ▁the ▁ 1 6 th ▁century , ▁when ▁the ▁city ▁corpor ation ▁built ▁a ▁new ▁bath ▁( Que en ' s