Mine is over 150 years old. It's had a new boiler and radiators, some insulation, a lot of redecorating and plastering, carpets, rewiring, a new kitchen, extensive floor tiling, and new upstairs bathroom. I love and hate it..
The damp in the utility room is a constant battle, it eats cash in heating oil, it's pebbledashed which hides the beautiful original stone walls (pebbledash is from I think the 1980s) which is apparently wrong for the stone walls and is a future issue...if not a current issue, most likely.
Also had to raise the back garden to solve a draining issue. Rebuild the boundary stone walls (a fucking literal nightmare job). It still needs some damp internal walls ripping off and sorting, three new exterior doors at great expense, and something doing to the uninsulated freezing box of an extension. I've somewhat ran out of steam ~and cash~.
Oh and the staircase is a bit rotten, every time I hoover it, woodlice come out. I've had booklice in the utility room (and inside my bread machine!!! 🤮), slugs coming up the sink, a suspected mouse in the loft, sparrows in the eaves. But when the wind blows, and the heating is finally warm, the two foot thick walls and the views of mountains outside just feel so cosy and good.
I curse it though when I'm sucking litres of condensation off the windows on cold mornings with the little hoover thingy 😅