Byrd Wrote:
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> Not as good as modern standards, according to this
> manual of construction tolerances:
> [catalogimages.wiley.com]

Nice, that's helpful!
Ok, the GP would not conform to ISO 4463 (published 1989) regarding its ground square dimensions as its 14cm length deviation for the 230m side length from the shortest to the longest of the 4 would be larger than the 6cm limit for that norm.

But isn't it remarkable how that old building reaches 42% of that modern norm, which requires high precision optical instruments at the construction sites?

Now the next step is to check the vertical alignment of the GP's foundation.