cription , ▁and ▁officially ▁opened ▁on ▁ 2 5 ▁July ▁ 3 1 5 . ▁Not ▁only ▁did ▁the ▁Roman ▁sen ate ▁give ▁the ▁arch ▁for ▁Const antine ' s ▁victory , ▁they ▁also ▁were ▁celebr ating   dec enn ia ,   a ▁series ▁of ▁games ▁that ▁happens ▁every ▁de cade ▁for ▁the ▁Rom ans . ▁On ▁this ▁occasion ▁they ▁also ▁said ▁many ▁pray ers . ▁However , ▁Const antine ▁had ▁actually ▁entered ▁Rome ▁on ▁ 2 9 ▁October ▁ 3 1 2 , ▁amid st ▁great ▁rejo icing , ▁and ▁the ▁Senate ▁then ▁commission ed ▁the ▁monument . ▁Const antine ▁then ▁left ▁Rome ▁within ▁two ▁months ▁and ▁did ▁not ▁return ▁till ▁ 3 2 6 . ▁ ▁The ▁location , ▁between ▁the ▁Pal at ine ▁Hill ▁and ▁the ▁C ael ian ▁Hill , ▁sp anned ▁the ▁ancient ▁route ▁of ▁Roman ▁triumph s ▁( V ia ▁triumph alis ) ▁at ▁its ▁origin , ▁where ▁it ▁diver ged ▁from ▁the ▁Via ▁sac ra . ▁This ▁route ▁was ▁that ▁taken ▁by ▁the ▁em per ors ▁when ▁they ▁entered ▁the ▁city ▁in ▁triumph . ▁This ▁route ▁started ▁at ▁the ▁Camp us ▁Mart ius , ▁led ▁through ▁the ▁Circ us ▁Maxim us , ▁and ▁around ▁the ▁Pal at ine ▁Hill ; ▁immediately ▁after ▁the ▁Arch ▁of ▁Const antine , ▁the ▁process ion ▁would ▁turn ▁left ▁at ▁the ▁Meta ▁Sud ans ▁and ▁march ▁along ▁the ▁Via ▁sac ra ▁to ▁the ▁Forum ▁Roman um ▁and ▁on ▁to ▁the ▁Capit oline ▁Hill , ▁passing ▁through ▁both ▁the ▁Arch es