This map has a discussion topic which can be visited here

Layout: A large Canyon with a tower, a bunker, and two turrets. The tower contains an elevator that leads to the tunnel system. The tunnel system contains two other rooms: the Fifties Room (because it uses the fifties texture set) and the President's Room (because it has a picture of the whitehouse in it). Eventually the tunnels lead to the garage and then back to the canyons.
The map was constructed with great care, and contains too many secrets to list. See the readme for some clues...