Left 4 Dead/The Hospital

You start in the emergancy ward of the hospital, and need to reach the roof.

Paths
Mercy hospital generally has one path throughout the building - make a beeline to the elevator by going up stairs whenever possible and remaining in the main corridors.

Even the upper portion of the hospital is linear - follow the outside portion of the renovations to reach the central area before reaching the safe house.

Traps

 * The elevator is both noisy and slow.