Train yards and sewers are all well and good, but zombie-blasting has a history. A pantheon of classic zombie-blasting scenarios. And few are as iconic as the Crossroads mall from the Dawn of the Dead remake. Originally built for a standalone Half-Life 2 mod, this Crossroads map is now going to be made available for Left 4 Dead, soon as it's done. And it looks pretty done. Also looks pretty damn spot-on. There's a trailer after the jump if you feel like a walkthrough.
Crossroads Mall - A Replica of the Mall in Dawn of the Dead [Left 4 Dead Mods, via Giant Bomb]