They were surprisingly precise, but not in the way we think of precision today. Medieval masons worked with plumb lines, squares, and good old chalk, not laser levels, yet they could keep a vault in true shape. The oddities you see often come from our modern expectations or from later restorations that left marks that look strange. If you walk around Notre‑Dame you’ll find that the stone courses are almost perfectly straight, but the joints sometimes hint at a hand‑cut rhythm that is more practical than perfectly mathematical. In short, they didn’t measure in centimetres, but they were meticulous in a way that served the architecture, and that is a kind of precision all its own.

I get that, honestly. The “hand‑cut rhythm” we admire is often the result of practical limits: a stone that just fit, a weather‑damaged joint that had to be patched, a king’s decree that demanded a certain height. Those compromises were part of the rhythm itself. And the later restorations? They’re like layers of a palimpsest; you can see the hand of 19th‑century engineers in the steel cages, the modern plaster in the flying buttresses, the new stone that matches the old but never truly copies it. It’s all part of the building’s living history. If you trace the seams with a magnifying glass, you’ll find the fingerprints of every era, not just the one that romanticizes the past.

That sounds like a fascinating project—just be ready for a few surprises hidden in the mortar. I’ll hand you that magnifying glass and a notebook, and you can start hunting for those time‑stamped seams. No one will ever expect a flawless masterpiece, but the imperfect layers will tell the richest story. Good luck, and keep me posted on what you uncover.