2 ▁BC , ▁the ▁P ons ▁A em il ius , ▁later ▁named ▁P onte ▁Rot to ▁( bro ken ▁bridge ), ▁is ▁the ▁oldest ▁Roman ▁stone ▁bridge ▁in ▁Rome , ▁Italy . ▁ ▁The ▁largest ▁Roman ▁bridge ▁was ▁Tra jan ' s ▁bridge ▁over ▁the ▁lower ▁Dan ube , ▁constructed ▁by ▁Ap oll od orus ▁of ▁Dam asc us , ▁which ▁remained ▁for ▁over ▁a ▁mill en ni um ▁the ▁longest ▁bridge ▁to ▁have ▁been ▁built ▁both ▁in ▁terms ▁of ▁overall ▁and ▁span ▁length . ▁They ▁were ▁most ▁of ▁the ▁time ▁at ▁least ▁ 2 ▁metres ▁above ▁the ▁body ▁of ▁water . ▁ ▁An ▁example ▁of ▁temporary ▁military ▁bridge ▁construction ▁are ▁the ▁two ▁Ca esar ' s ▁Rh ine ▁brid ges . ▁ ▁Lar ge ▁river ▁brid ging ▁ ▁Roman ▁engine ers ▁built ▁stone ▁arch ▁or ▁stone ▁pill ar ▁brid ges ▁over ▁all ▁major ▁rivers ▁of ▁their ▁Imper ium , ▁save ▁two : ▁the ▁Eu phr ates ▁which ▁lay ▁at ▁the ▁front ier ▁to ▁the ▁rival ▁Pers ian ▁emp ires , ▁and ▁the ▁N ile , ▁the ▁longest ▁river ▁in ▁the ▁world , ▁which ▁was ▁' brid ged ' ▁as ▁late ▁as ▁ 1 9 0 2 ▁by ▁the ▁British ▁Old ▁As wan ▁Dam . ▁ ▁The ▁largest ▁rivers ▁to ▁be ▁sp anned ▁by ▁solid ▁brid ges ▁by ▁the ▁Rom ans ▁were ▁the ▁Dan ube ▁and ▁the ▁Rh ine , ▁the ▁two ▁largest ▁European ▁rivers ▁west ▁of ▁the ▁E uras ian ▁Ste ppe . ▁The ▁lower ▁Dan ube ▁was ▁crossed ▁by ▁least