Those walls don't look very thick. When I was a stonemason in France we built walls twice that thick, and with undressed stone. We worked the traditional way, with lime mortar, and building the scaffolding into the wall as we went up. While I never worked on any castles, I did work on a house that was built in around 1200 A.D. I'd love to build my own house out of stone some day, but I'm definitely not at that point yet in my life - I still don't know what I want to be when I grow up (I'm 30 now).

Andrew.