▁built ▁by ▁the ▁ 1 9 th ▁century ▁industrial ist ▁and ▁phil anth rop ist ▁Sir ▁Tit us ▁Salt ▁after ▁he ▁observed ▁other ▁text ile ▁fact ories ▁and ▁was ▁disappoint ed ▁by ▁the ▁working ▁conditions ▁he ▁saw ▁there . ▁At ▁the ▁time ▁mill ▁working ▁conditions ▁were ▁commonly ▁poor , ▁with ▁most ▁workers ▁suffering ▁disease , ▁low ▁w ages ▁and ▁labour ▁explo itation . ▁D anger ous ▁mach in ery ▁and ▁long ▁hours , ▁sometimes ▁exceed ing ▁ 1 6 ▁hour ▁working ▁days , ▁resulted ▁in ▁frequent ▁acc idents . ▁Tit us ▁Salt ▁acknowled ged ▁this ▁and ▁built ▁a ▁factory ▁and ▁surrounding ▁town ▁with ▁which ▁he ▁intended ▁to ▁improve ▁the ▁working ▁conditions ▁for ▁his ▁employees . ▁When ▁completed , ▁the ▁mill ▁was ▁the ▁largest ▁industrial ▁building ▁in ▁the ▁world ▁by ▁total ▁floor ▁area . ▁ ▁It ▁is ▁a ▁grade ▁II * ▁listed ▁building . ▁ ▁The ▁mill ▁closed ▁in ▁ 1 9 8 6 ▁and ▁the ▁following ▁year ▁it ▁was ▁sold ▁to ▁Jonathan ▁Silver , ▁who ▁began ▁a ▁long ▁renov ation ▁scheme . ▁ ▁Sp elling ▁ ▁The ▁spell ings ▁Sal ts ▁Mill ▁and ▁Salt ' s ▁Mill ▁( that ▁is , ▁with ▁and ▁without ▁an ▁apost rop he ) ▁are ▁both ▁commonly ▁used . ▁The ▁former ▁is ▁used ▁consist ently ▁by ▁the ▁Sal ts ▁Mill ▁website ▁and ▁the ▁Sal taire ▁Village ▁website ; ▁the ▁latter ▁by ▁Vis it ▁Brad ford ▁from ▁the ▁official ▁Brad ford ▁Tour ist ▁Information ▁service . ▁Both ▁versions ▁are ▁used ▁in ▁the ▁UN ES CO ▁World ▁Heritage ▁documentation .