Instructions
Go to the corner of the crossfire map and stand by the tall building.
Jump on top of the chair sitting against the building and walk as far to the left on the chair as possible without falling off. Jump on top of the ledge. Run and jump to the next ledge positioned to the right of the first ledge.
Walk to the upper left corner of the large slab and jump up to reach the upper level of the building. Jump to the building with a white roof.
Get a friend to crouch on the edge of the building. There's an invisible wall glitch. Run and jump on top of your friend's body. This will suspend you in mid-air and you can move as you please.
Take a left and continue walking until you reach another wall in the corner, where you will drop down a few inches. Continue walking along the wall until you reach the ledge next to the power lines.
Take two lefts, continuing to walk along the ledges, then take a right. Walk forward until you reach the air conditioning unit sticking out of the wall. Jump on it, then jump on top of the balcony. You'll be in an excellent, protected sniping location.