I started my working life in the lift industry........... Scaffold inside a lift shaft was never tied back to anything, so that we could get to all of the walls........ you could really get them shaking and waving up and down the shaft!
That cured my fear of heights and also taught me (as a young apprentice) never to work below others on a scaffold!
I finished my apprenticeship and then worked as a design engineer on the Nat West Tower refurb (early / mid 90's)....... I drafted the machine room on scaffold boards over 3 days, before someone lifted a board to show me a 42 storey shaft below.......... Talk about pooping myself after the event!! LOL