Took five seconds to crudely destroy the lines between same shades of bricks. I don't think it looks flat.
Yeah thats the idea. It makes it look like some bricks stick out/in more than others etc.
I'm not sure but I think you'll find that erosion aside, there still would have been some randomness to the bricks such as
http://www.toptenz.net/wp-content/uploads/2009/08/Troy1.jpgAlso good to mix up the shape geometry of the wall with some structural shapes such as in that image.
You wouldn't want vines all over every wall but there might be one bit where there is a garden inside and some vines have grown over.
Things like that can obviously help break it up a bit too although I don't know if that would have been allowed on the outer wall for security purposes...
