Fun fact: late Romans used concrete, so thinking that they couldn't produce near perfect bricks is more far fetched than thinking they could. Also, there was a culture, I think an Andean culture, that used stone to chip stone, and had no mortar, but created perfect fitting blocks for their buildings. Each one was done on the spot, not premade. Not sure what culture it was though. Could have been the Inca for all I know, its been a long time since I brushed up on south American history.
And back on track, the wall isn't meant to look perfectly new, but not old either. When I look it seems like its got just the little bit of weather I'm aiming for, but if you guys don't think so I'd happily work it some more. As of now I haven't quite shit a roadblock, more like thick, sticky mud. I'll keep going till I get a significant enough change to post.