Go straight ahead and through the arch. In the open area after the arch will be stairs down to the left. Locust will attack Marcus and Dom. Go down the stairs.
Straight ahead and to the left will be an opening. Go through the opening and in the small cemetery more Locust will attack.
After the Locust are dead, Continue straight in to the cemetery and up the stairs in the back.
At the top of stairs a group of Locust will attack from the left. One will be a Troika gun emplacement. If you have a Torque Bow shoot a arrow at the Troika and it will stick.
The resulting explosion should kill the locust manning it.
When the Locust are dead. Head to the left of where you entered this area. Go through the arch. To the right will be some stairs down. There is another Troika down there. Use the
Torque Bow again. When the troika is dead, go through the next arch.
Follow this path until you reach the right turn. Follow the right path up the stairs. When you reach the left turn, go forward until you reach a gate. Kick the gate open.