In reply to Hazelnuts: I used to do parkour, the trick is not to get caught. Lol. To be honest, jumping around on steps, climbing walls etc we never got in any trouble. Ion the odd occasion we would have the owner or worker come out and have a moan. We was always respectful and left without a fuss. I would imagine these principles would apply to Buildering. Doing big stuff though, yes that would draw attention and its also the impact to the little boy passing by if you slip watching you splat infront of him amongst a whole host of other possible outcomes, like damaging the building, causing a crowd, etc etc.
When we done big parkour projects it would be planned and fast, so it was over before anybody noticed and always had an escape planned.
I think thats part of the appeal though isn't it, not just scaling a huge building, but getting away after, not getting caught, just seen.
Personally I think the world is our playground, and that's what I think its intended to be. Enjoy.