Incidentally, one of the cool/frustrating things I've learned after a decade of living in various older masonry buildings is that you actually *can't* insulate them very much without fucking up the moisture balance.
Every masonry wall takes on water through leaks and the natural porosity of the brick/stone. That moisture has to leave the wall cavity through open joints or weeps. If you've ever seen those little pieces of rope hanging off a brick building, they're to let water wick out!
Cavity walls (2000+ years old!) allow air circulation within the wall, and damp-proof courses cut off capillary action from the soil.
https://npshistory.com/publications/preservation/masonry-walls-moisture.pdf
But the problem of moisture balance is way, WAY more complex than that. There's vapor pressure and thermal effects for each layer of the wall, and those forces change throughout the year with internal and external heating and moisture.
https://www.wbdg.org/resources/moisture-management-concepts is hands-down the best overview I've come across for this problem.
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