Get on the elevator and go down to the street. Take the same path you took for the last two missions, but this time after crossing the light post bridge hug the left side near the gap and start climbing on the first pipe that you see.
Make your way to the other side of the billboard and climb down there. Now keep close to the gap and start walking to the right side of where you are.
Your path will eventually get blocked by a huge gap on the street. Move over to the right side of the street when you hit the gap and continue moving forward.
After crossing the gap, turn left and you'll find a beam support that stretches towards one of the buildings. Cross it and climb up the beam on the left.
Start walking towards the building pillar and jump up on it, then make your way to the pipes on the side and use those to climb up into the collapsed wall of the building.
Press space when you get to the open area and start dropping down from the opposite side.
Crouch down and go in through the open door. Now jump up on the second open door and pull yourself up.
Climb up on the wall that separates the shower and toilet, then turn left and climb up on the pipe. Move to the left and climb up to the next stall.
Face the wall on the right, shimmy to the left and climb up through it. Now look at the wall on the left side and jump on the pipe, then shimmy along the vents to the right and drop down on the other side.
Drop down the drapped side of the area and it will go dark. Just keep dropping down until there's nowhere to drop on.
Look to your right and you'll find a light source coming from that side. Proceed towards it and exit through the next area.
Make your way down to the lower floor and jump down on the open door furthest away from the platform you dropped down from.
You'll be stepping on a beam now, turn left and drop down on the pipe. Keep going towards the right from there.
When you get to the end of the first pipe, drop down and use the vents to continue to the right. On the last vent drop down on the metals below and jump across each one until you get on the last pipe. Now drop down on the floor.
Cross to the other side and walk on the glass frames to get on the glass pane that's sticking out towards the wall. When you get there, jump on the vents and make your way to the left.
Then climb up and start heading to the right once you get to the third row. From there climb up the pipes and jump towards the ledge on the next floor. Then pull yourself up.
Head forward outside and grab the piton there, then get back inside and turn right at the curtain. Look behind you and start climbing up on the pipes.
When you get to the top, walk up the fallen mesh gate and jump on the ledge in front of it.
Now head around the rubble and climb up on the ledge that leads to the exterior of the building. Pull yourself up and walk towards the destination marker.