Sewers

The Sewers is a map in that takes place in an underground sewage system, it's a downloadable map after players have completed the Cemetery.

Layout/Strategy
Most of the area is made up of narrow corridors with air vents and holes serving as spawn points for the infected. There are three large rooms, one in the center, the second one being at the top left corner and the third room is at the top right just a short walk from the small room. Any weapon with high power and high clip capacity would work fine.