It's the example map for Source Compo 1 - Deathmatch from floor plan! Ok, so it isn't the best map in the world, but I made it in a day, and it's just an example.
Also, it's worth noting that I've whored out the most generic theme possible. Now, I'm begging people to not do anything remotely similar to mine.
How do you make such nice turns?
The textures are turning to,, you know..
Is the turn made by several brushes, so you rotate the texture for ech brush? :S
Or is it some other trick?