I recall during my brief vac job (summer 1967) as crane driver's mate at British Celanese, we had to dismantle some plant supported by a steel framework at least as tall as the skeleton of the Locarno/Library stairwell. The floors at each stage, some of which had been removed to gain access, were made from galvanised steel grids resting on the girders. I remember having to walk along the tops of girders with perhaps a 50 foot drop on either side.

Normally petrified of heights, in the context of the working environment I somehow accomplished this without thinking about it!