I'm done with the walls and started to test with bots.
This is A. To the left is CT spawn, from the right is one path for T and to the upper right another.
This is B. The Ts can take a risky path to cover the bomb from the roof on the right. CTs are coming from the lower left or the canal.
This is T spawn. It's going to be some kind of restaurant. The path to the left is going to be an old street.
This is CT spawn. The garage of a bank.
And here a view on the canal area in the center of the map.