After being rescued from the Blood Harvest you find the driver of your rescue vehicle has become infected, and has crashed behind a massive asylum. The Trans-Allegheny Lunatic Asylum.
The beginning of my map takes place under a water tower up on a hill.
Well there wasn't a water tower model in L4D that fit the look I was going for.
I wanted a old style metal water tower similar to one in a tourist town near me:
Flickr.com
All of the model was made in sketchUp and textures were tweaked in Hammer.
Again, not the final product, but a placeholder so that the map can develop around it.
The tower is shorter for two reasons: Smokers can smoker someone on the ground from the walkway, and a full scale tower is so ridiculously tall when you stand under it that it's loosed its iconic look. There is a infected ladder on one side.