Pipeline

Pipeline is a large multiplayer map in Call of Duty 4. It's main design centers around two side-to-side warehouses out in the middle of Russia (or somewhere exotic) and the immediate areas around it.

Gameplay
The map features a good variety of sniper positions throughout the level. Including on top of the roofs of the two main warehouses, and the green hill they both face.

The level also has a rather elaborate network of tunnels beneath it. These tunnels can provide undetected movement from one location to another, as they mostly go unused by many players. But sometimes other players may decide to use them, so don't let your guard down completely.