ird ers ▁and ▁other ▁required ▁parts . ▁ ▁The ▁bridge ▁is ▁held ▁together ▁by ▁six ▁million ▁Australian - made ▁hand - dri ven ▁riv ets ▁supplied ▁by ▁the ▁Mc Ph erson ▁company ▁of ▁Melbourne , ▁the ▁last ▁being ▁driven ▁through ▁the ▁deck ▁on ▁ 2 1 ▁January ▁ 1 9 3 2 . ▁The ▁riv ets ▁were ▁he ated ▁red - hot ▁and ▁inserted ▁into ▁the ▁pl ates ; ▁the ▁head less ▁end ▁was ▁immediately ▁rounded ▁over ▁with ▁a ▁large ▁p neum atic ▁riv et ▁gun . ▁The ▁largest ▁of ▁the ▁riv ets ▁used ▁we ighed ▁ ▁and ▁was ▁ ▁long . ▁The ▁practice ▁of ▁riv eting ▁large ▁steel ▁structures , ▁rather ▁than ▁w eld ing , ▁was , ▁at ▁the ▁time , ▁a ▁proven ▁and ▁understood ▁construction ▁technique , ▁whilst ▁struct ural ▁w eld ing ▁had ▁not ▁at ▁that ▁stage ▁been ▁ade qu ately ▁developed ▁for ▁use ▁on ▁the ▁bridge . ▁ ▁P yl ons ▁At ▁each ▁end ▁of ▁the ▁arch ▁stands ▁a ▁pair ▁of ▁ ▁concrete ▁p yl ons , ▁faced ▁with ▁gran ite . ▁The ▁p yl ons ▁were ▁designed ▁by ▁the ▁Scottish ▁architect ▁Thomas ▁S . ▁T ait , ▁a ▁partner ▁in ▁the ▁architect ural ▁firm ▁John ▁Burn et ▁& ▁Part ners . ▁ ▁Some ▁ 2 5 0 ▁Australian , ▁Scottish , ▁and ▁Italian ▁st on em asons ▁and ▁their ▁families ▁re located ▁to ▁a ▁temporary ▁settlement ▁at ▁Mor u ya , ▁NS W , ▁ ▁south ▁of ▁Sydney , ▁where ▁they ▁quar ried ▁around ▁ ▁of ▁gran