need some terrainage (very small map)

ok, i've attached a small map which i need some terrain help with. I basically provided whoever wants to tackle this problem with a basic theme of what i need. Some other things i need are:

1. There's a marine "hiding" in some rocks, these are not needed in the final project, i just want a few spaces where i you can stick a unit like that and it won't be too wierd for you not to be able to see it there.

2. The map needs to be a section of a city, and the boundries need to be somehow NATURALLY blocked (i.e. a collapsed bridge, road covered in rubble, houses), no random bridge going off to somewhere.

3. Some random mobjects in the middle that can again be "hid behind". for insance, a house in the middle will shield anything on the other side from view.

4. The map will be an arena-type map where meanies involved as well so keep this in mind when terrainisizing. Maybe a few areas where there can be some serious creep "density" would be nice.

5. All buildings need to be ruined.

6. THX SO MUCH IN ADVANCE.

7. Oh, and this *should* be understood but with the current state of things it might not hurt to mention: I give credit.

i changed it around a bit... the marine is no longer there and i added a right side (feel free to change what you wish)

The situation with the marine was:
where X was rocks and O was the marine.

Is it alright if I change like, everything? And by arena you mean like, an urban assault type of map?

ya sure, change everything... i just wawnt the theme to remain the same. And by arena i mean theres going to be one hero controlled unit per player in it and a bundch of monsties.