▁river ▁and ▁the ▁Bar le ▁Valley ▁are ▁both ▁designated ▁as ▁bi ological ▁Site ▁of ▁Special ▁Scient ific ▁Interest . ▁The ▁river ▁passes ▁under ▁the ▁T arr ▁Ste ps , ▁a ▁pre histor ic ▁cla pper ▁bridge ▁possibly ▁d ating ▁from ▁ 1 0 0 0 ▁BC . ▁The ▁stone ▁sl abs ▁we igh ▁up ▁to ▁ 5   tons ▁each . ▁According ▁to ▁local ▁legend , ▁they ▁were ▁placed ▁by ▁the ▁devil ▁to ▁win ▁a ▁bet . ▁The ▁bridge ▁is ▁ ▁long ▁and ▁has ▁ 1 7 ▁sp ans . ▁It ▁has ▁been ▁designated ▁by ▁English ▁Heritage ▁as ▁a ▁grade ▁I ▁listed ▁building . ▁The ▁other ▁brid ges ▁over ▁the ▁Bar le ▁include ▁the ▁five ▁span ▁Bar le ▁Bridge ▁which ▁is ▁medieval ▁in ▁origin . ▁It ▁has ▁double ▁rings ▁on ▁the ▁down stream ▁side ▁and ▁single ▁rings ▁on ▁the ▁up stream ▁side . ▁It ▁was ▁rep a ired ▁in ▁ 1 6 2 4 , ▁and ▁subsequently ▁w iden ed ▁in ▁ 1 8 1 9 ▁by ▁John ▁Stone . ▁It ▁was ▁further ▁rep a ired ▁in ▁ 1 8 6 6 ▁and ▁in ▁ 1 9 5 2 – 1 9 5 3 ▁after ▁flo od ▁damage . ▁The ▁ 1 8 th - century ▁Marsh ▁Bridge ▁was ▁alter ed ▁in ▁ 1 8 6 6 ▁when ▁the ▁central ▁pier ▁was ▁removed ▁and ▁an ▁iron ▁bridge ▁inserted . ▁The ▁par ap et ▁was ▁destroyed ▁in ▁ 1 9 5 2 ▁and ▁re construct ed ▁in ▁steel ▁in ▁ 1 9 7 9