The wall where I climb (Harlow) has a little concrete pyramid outside with gritty sprayed-on concrete providing the routes. I've been wanting to climb on it for ages, and this week thought to ask if it was possible. Ropes duly appeared (you have to use their provided top-ropes on it), and we had fun! A couple of entertaining crack climbs which you don't get on indoor walls much.

The resulting midge-bites are less good though :-s