▁ 6 . 5   m ▁wide ▁and ▁the ▁later als ▁ 7 . 4   m ▁by ▁ 3 . 4   m ▁each . ▁The ▁arch ▁is ▁constructed ▁of ▁brick - fac ed ▁concrete ▁re vet ed ▁in ▁mar ble . ▁ ▁The ▁three ▁bay ▁design ▁with ▁det ached ▁columns ▁was ▁first ▁used ▁for ▁the ▁Arch ▁of ▁Sept im ius ▁Sever us ▁in ▁the ▁Roman ▁Forum ▁( which ▁stands ▁at ▁the ▁end ▁of ▁the ▁triumph ▁route ) ▁and ▁repeated ▁in ▁several ▁other ▁arch es ▁now ▁lost . ▁ ▁Though ▁dedicated ▁to ▁Const antine , ▁much ▁of ▁the ▁sculpt ural ▁decor ation ▁consists ▁of ▁relief s ▁and ▁stat ues ▁removed ▁from ▁earlier ▁tri um phal ▁monuments ▁dedicated ▁to ▁Tra jan ▁( 9 8 – 1 1 7 ), ▁Had rian ▁( 1 1 7 – 1 3 8 ) ▁and ▁Marcus ▁A ure lius ▁( 1 6 1 – 1 8 0 ). ▁ ▁History ▁ ▁The ▁arch , ▁which ▁was ▁constructed ▁between ▁ 3 1 2 ▁and ▁ 3 1 5 ▁AD , ▁was ▁dedicated ▁by ▁the ▁Senate ▁to ▁comm emor ate ▁ten ▁years ▁( dec enn alia ) ▁of ▁Const antine ' s ▁reign ▁( 3 0 6 – 3 3 7 ) ▁and ▁his ▁victory ▁over ▁the ▁then ▁reign ing ▁em peror ▁Max ent ius ▁( 3 0 6 – 3 1 2 ) ▁at ▁the ▁Battle ▁of ▁Mil v ian ▁Bridge ▁on ▁ 2 8 ▁October ▁ 3 1 2 , ▁as ▁described ▁on ▁its ▁att ic ▁ins