There's a map I used to play years ago that I cannot find because I don't know the name. If the following quick description rings a bell please message back with a map name! :)
I used to play it on gungame servers. You start off in a house, you can't go outside unless you go in to the middle of the house where there is a tiny courtyard. Its raining. There are two floors and a small basement where you can turn the lights on and off. Its a fairly dark map. Some of the door ways have board that you can shoot out and crawl under.
I'm fairly certain that CTs start at the top floor and immediately available to them is a stairway to go do the bottom floor/corridors. Its not a big map, great for 4 on 4 or more play.
If anyone has the name please let me know.