After climbing up to the opening overlooking the DEAD-END ALLEY WITH THEBLOCK AND CRAWLSPACE, as shown in the previous section...

...take a running jump to grab the edge of the roof next to the broken machine gun.

Pull up and take the revolver ammo lying next to the machine gun. Go through the door you opened earlier and follow the passageway to the end.

NOTE: If this door is still closed, see the note in the main walkthrough.

If you didn't destroy the 2 machine guns on the rooftop earlier, enter this area cautiously. Move out beyond the end of the first low wall and turn right to face the guns.

Lara is safe as long as you don't get too close. Once you pass the far edge of the low wall, the motion sensors will activate, and the guns will start firing. Now aim at the red fuel barrel on the roof between the guns and the helicopter in the background.

You can use the pistols and just tweak Lara's angle until you're able to hit the barrel...

...or use the revolver and laser sight (with or without the laser sight bug).

Shooting the barrel sets off a chain reaction that destroys the helicopter and both guns. If you already destroyed the guns earlier, you can still do this just to watch a cool explosion. :D

Move to the edge of the roof. (Note the gate below. This is where you parked the motorcycle earlier after that frantic ride under the guns.) Take a running jump from the jutting ledge to grab the ledge on the other side of the street, where the guns were. Pull up and make your way to the back left corner.

Pick up a small medipack and use the lever...

...to open the gate below.

[City of the Dead Walkthrough]