el ict ▁military ▁structures , ▁probably ▁p ump - h ouses ▁supp lying ▁water ▁for ▁the ▁Blue ▁Stre ak ▁ro cket ▁site ▁at ▁R AF ▁Sp ade ad am , ▁can ▁be ▁seen ▁just ▁up stream . ▁Further ▁down stream , ▁in ▁the ▁grounds ▁of ▁G ils land ▁Sp a ▁hotel , ▁the ▁c rag s ▁develop ▁into ▁high ▁cl iffs . ▁The ▁cl iff ▁face ▁below ▁the ▁hotel ▁gives ▁rise ▁to ▁the ▁famous ▁sul ph ur ous ▁spring ▁after ▁which ▁the ▁hotel ▁is ▁named ▁and ▁also ▁a ▁ch aly be ate ▁spring ▁and ▁a ▁pet r ifying ▁se ep . ▁▁ ▁Had rian ' s ▁Wall ▁crossed ▁the ▁river ▁on ▁a ▁bridge ▁at ▁Will ow ford , ▁ 0 . 7 5 ▁kilometres ▁( 0 . 5 ▁miles ) ▁east ▁of ▁Bird os wald ▁Roman ▁Fort . ▁From ▁that ▁point ▁the ▁course ▁of ▁the ▁river ▁as ▁it ▁turns ▁west ▁is ▁l ined ▁with ▁other ▁Roman ▁sites ▁associated ▁with ▁the ▁Roman ▁Stan eg ate ▁road ▁and ▁Had rian ' s ▁Wall . ▁A ▁ 9 1 4 - met re ▁( 2 , 9 9 8 . 7 ▁feet ) ▁stretch ▁of ▁Wall , ▁including ▁two ▁tur rets ▁and ▁the ▁impress ive ▁bridge ▁remains , ▁runs ▁alongside ▁the ▁River ▁Ir thing ▁at ▁Will ow ford , ▁linked ▁by ▁a ▁new ▁foot bridge ▁to ▁Bird os wald ▁Roman ▁Fort . ▁This ▁crossing ▁of ▁the ▁River ▁Ir thing ▁marked ▁a ▁significant ▁transition ▁in ▁the ▁construction ▁of ▁Had rian ' s ▁Wall , ▁emphas ising ▁the