Continue down the corridor you are in. In the next room you are approaching is The Bridge. Run through.
A Force of Cabal is waiting in here for you. You must fight through to the far side of the room, to the left. There is a mix of Phalanx and Legionaries below you. Expect at least one Colossus in the mix as well. When you defeat all the enemies inside the room, the door forward will open. Head on through it.