[onion2k]

I'm not a civil engineer so I don't know for sure, but I'd guess you can't just throw a cathedral up just anywhere you want. The land has to be the right composition, you need to have good enough transport links to get the raw materials to where you're building it, you need local talent to actually build it, it can't be in the sea.

It'd be surprising if these buildings were exactly aligned. Presumably people could easily say that the respective diocese(s) are aligned though.

[lloeki]

Tell that to the people that decided that Strasbourg should have a cathedral: the whole area is a freaking swamp (water table + sand and clay). Not to fret, they punched 15cm x 1.5m tree trunks into the ground, as if you were standing on a thousand toothpicks.

Local myth has it that the second spire wasn't build because it would topple over.

Probably many more examples like this one exist. "I don't care. Figure it out. You're the expert."

https://m.youtube.com/watch?v=BKorP55Aqvg

[johncalvinyoung]

Salisbury Cathedral (highest medieval spire surviving in the UK, at 404 feet!) was built on a floodplain close to the river, with shallow foundations only four feet deep. But the prior cathedral had been on a hilltop with much strife over access to water, and at least that would not be a problem at the new cathedral.

https://salisburycathedral.wordpress.com/the-spire/ is a glorious essay on the architecture of that spire.