Presumably we also find masonry spiral stairs in contemporary churches, cathedrals, bell towers, monasteries, storage cellars, etc. - do these structures (which

Presumably we also find masonry spiral stairs in contemporary churches, cathedrals, bell towers, monasteries, storage cellars, etc. - do these structures (which one assumes have very different threat models to a castle) exhibit similar bias? Romans built spiral staircases as well - did they favor a particular direction? What about other cultures unrelated to European castle building traditions? Honestly, though, if you’ve ever worked on a construction project you would know: even if you had a record of a papal decree mandating that all staircases must turn to the right, multiple books documenting how to build staircases with a right turn and warning against left-turning designs, and original castle drawings showing the architect marked explicitly that the staircase must turn right, it would not be surprising to find that 30% of staircases turn left just because the contractor installed it backwards.