From your start position in the sewer, run through the tunnels until you reach a ladder, then climb this to reach the surface. During this Bridge, Arno will be subjected to gunfire if he is illuminated by searchlights. Climb over the tank to pass the first searchlight. When you reach the base of the tower, approach the broken fence section and begin climbing. As prompted, use 
/
to encourage Arno to jump whenever he pauses during the ascent. Angle your climb to avoid the searchlight when you approach it.
When Arno climbs onto the ledge, run forward until he automatically moves beneath the tower. Follow the route shown here to reach the platform on the far side, moving purposefully during the wall ascent to avoid a searchlight.
At the platform, turn left and enter the lift shaft for the next ascent. Press 
/
to reach higher ledges whenever Arno pauses, and stay on the right-hand side to avoid an electrical hazard. At the top, move right to grab the ladder, climb it, then go through the door.
Follow the path until a plane flies towards Arno, then immediately move towards the nearby crate and press 
/
to snap to cover. Once the plane has passed, run over to the machine-gun emplacement and press 
/
to control it. Fire at the attacking plane with 
/
, taking care to hold 
/
to take cover when it makes an attack run. It’s usually safe to continue firing for a few seconds when this begins. When the plane explodes, follow the route illustrated above to reach the Zeppelin and, from there, a platform on the tower.
From the platform, begin your ascent to the top of the tower by using the lift rope, then stay on the left-hand side and pause, if required, to pass the searchlight without incident. Arno will automatically climb through the girders. Climb on top of the elevator to trigger a brief cutscene.
Climb the small ladder and head up the steps. After the barrage of gunfire, you must man the nearby machine gun and shoot down two planes. Start with the one that attacks from the left, and err on the side of caution when hiding from their initial (near-synchronized) attacks. Naturally, it makes sense to focus your fire exclusively on one plane. When you’re done, follow the route shown here to reach a platform far above. Climb to the very top of the spire and perform a Leap of Faith through the replacement portal to conclude your journey through the Bridge.