EDIT:
here it is (this is a beta, but I may not finish it for a while). (thanks Dredge)
This is the beta version, because there are still some errors which I can't fix - everything seems correct but it just doesn't work. Feel free to decompile the bsp and sort them out (and then give me the new vmf). I've given up.
I've also changed the name to sf_flats, because sf_2flat was starting to annoy me after a while... though I wanted to allude to TFC

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Stay tuned for some screenshots, maybe. As if you care :P.
[OLD POST]
I'll submit it to the mappack people if anybody likes it, but I thought I'd give it it's own thread because I ended up writing far too much :?.
I was sick of nobody ever capturing the flag, so I set out to create a map that might have the pace of traditional CTF. Also, I'm sick of giant maps which are just big fields. I know they should be sparse, but so far most maps have been of the format "spawnzone + huge gap to build a fort" - I think SourceForts can be much more versatile than that.
It's set in a pair of abandoned blocks of flats, with three levels - the second story, the third story, and the roof.
The flats aren't joined in any way; it's impossible for a member of one team to enter the other team's flat without making use of physics objects. This will probably result in walkways between parts of the buildings, which allows the players to customise the possible routes around the map. This should be almost indescribably cool.
The flag is on the second story, because it's better to be above your enemy, so for good defence the defenders will have to be far away from the flag (though defending at a distance is not good, so there is no 'best' place to defend from - another feature which forces you to think about tactics). This might give some actual reason for people to build rooves on their outposts rather than just the pretense of 'grenade shields' :p.
Also, with the flag low down, attackers may find it harder to go directly to the flag, and will have to take an indirect route.
There are ladders and stairways to get between the floors, so this means that if the enemy has access to one floor, they have access to them all - unless you block off all the ladders, making it difficult to get around yourself. There are 4 windows on each floor, which have to be defended, plus the roof. Then there is the fact that the physics objects are only on the third story and the roof, not on the second story - it's quite hard to get stuff between floors, even if you build an external ramp. This is designed to stop people getting all the physics objects to the flag and just crowding it with them.
If you fall , there are team-only doors with which you can get back into your base - this also means that you don't have to run back the way you came, so you don't have to build an enterance to your base - this way, the enemy may have to build their own ramps around your fortifications, which should make for an interestingly competitive build time.
I've also not limited where people can build in any way, except by the physical dimensions of the map, which can be restrictive as to where you can take peices - you should be able to get stuff anywhere, but some windows take a lot of annoying block turning, so there's a decision between building stuff inside and the effort of getting the materials in.
I highly recommend turning damage on on this map. Then people will be able to shoot out bridges between windows, limiting the opponant's options. However, it's unlikely that anybody would destroy ALL the routes between flats, because then NOBODY could get between flats.
I also highly recommend turning melee weapons in build mode on. This is so that the enemy can be challenged when they come along and try to build ramps over your stuff.
Wow, that became a real essay

. Sorry. Here are some pictures I took, to give you a break from all that reading. Some of them are in low graphics, some are with the graphics set to the recommended setting for my computer - I don't think I ever got a frame rate below 50 (well, 49), and on low it was 80-250, which is not bad at all - I was worried that this map might be a bit of a system-hog, but it has fewer physics objects than most, so it's fine.
At the back of the lowest level, with the ball and some emptiness.
A picture of the blue base, with some absolutely terrible attempts at construction tacked on to it.
Those same terrible constructions through
Some boxes in a slightly-secret-but-not-very area. These came out a lot prettier than I expected, so I took a screenshot

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An attempt at building well. The full width of the building is in view.
Blocking the rear ladder.
This is my attempt at building well from a different angle. The skybox is crap in this shot, but I've improved it since then.
The above from below.
You CAN block the ball, but it took me quite a while to get these three plates in. Also, there's a ladder behind me which people can climb down, and red could come along with a long bit and build a ramp over... so it wasn't really worth it. Or was it?
This is the construction ramp I needed to get those three plates to the ball. In carrying something out, your options can change unexpectedly, and this ramp turned into a walkway to the enemy base too.
There are a few more pictures on my photobucket, I think.
I'll upload this later... it's as good as finished, but I've just got to make the lower passageway doors team-specific. If I can't work it out I'll just steal Dredge's killzones from sf_basin

. [/OLD POST][/b] :P