od ▁open ings ▁in ▁the ▁pi ers , ▁e . g . ▁in ▁the ▁P ons ▁Fab r ici us ▁in ▁Rome ▁( 6 2 ▁BC ), ▁one ▁of ▁the ▁world ' s ▁oldest ▁major ▁brid ges ▁still ▁standing . ▁Roman ▁engine ers ▁were ▁the ▁first ▁and ▁until ▁the ▁industrial ▁revolution ▁the ▁only ▁ones ▁to ▁construct ▁brid ges ▁with ▁concrete , ▁which ▁they ▁called ▁op us ▁ca ement ici um . ▁The ▁outside ▁was ▁usually ▁covered ▁with ▁brick ▁or ▁as hl ar , ▁as ▁in ▁the ▁Alc ánt ara ▁Bridge . ▁ ▁The ▁Rom ans ▁also ▁introduced ▁segment al ▁arch ▁brid ges ▁into ▁bridge ▁construction . ▁The ▁ 3 3 0 ▁m ▁long ▁Lim y ra ▁Bridge ▁in ▁south western ▁Turkey ▁features ▁ 2 6 ▁segment al ▁arch es ▁with ▁an ▁average ▁span - to - r ise ▁ratio ▁of ▁ 5 . 3 : 1 , ▁giving ▁the ▁bridge ▁an ▁unus ually ▁flat ▁profile ▁un sur pass ed ▁for ▁more ▁than ▁a ▁mill en ni um . ▁Tra jan ' s ▁bridge ▁over ▁the ▁Dan ube ▁featured ▁open - sp and rel ▁segment al ▁arch es ▁made ▁of ▁wood ▁( standing ▁on ▁ 4 0 ▁m ▁high ▁concrete ▁pi ers ). ▁This ▁was ▁to ▁be ▁the ▁longest ▁arch ▁bridge ▁for ▁a ▁thousand ▁years ▁both ▁in ▁terms ▁of ▁overall ▁and ▁individual ▁span ▁length , ▁while ▁the ▁longest ▁ext ant ▁Roman ▁bridge ▁is ▁the ▁ 7 9 0 ▁m ▁long ▁Pu ente ▁Rom ano ▁at ▁M ér ida . ▁ ▁The ▁late ▁Roman ▁Kar