650 meters. Obviously, I have a fear of heights.
I used to climb dragline and shovel booms to repair them. Often had to climb pipes that were covered with grease and with the handrails torn off from falling point sheaves.
Funny thing was that I was never afraid during the job (probably because it took too much focus to avoid falling) but after the really dangerous shifts I always thought about falling when I laid down in bed to try to sleep.
The worst was when we had to walk the stick on a power shovel, which was basically a 12' diameter horizontal pipe about 100' long covered with grease. Had to make sure that every step was on the dead center of the pipe. Any step off center would have meant a quick trip to the ground.