Ours is about 1600, an old detached corn mill that was converted to residential use about 150 years ago. It's not listed - unlike our two neighbours (the former stable block and the mansion to which ours and the stables once belonged) - although the crenellated wall that forms part of the garden boundary is.
We still have the (drained) leat running through our land and traces of where the water wheel stood as well as the outlines of the original windows, some of which were reduced in size/moved when the building became a house. We also have an undercroft but this is currently not habitable space.
Sadly, because it was converted in the Victorian era and isn't listed, internally few of the original features remain and those that do are predominantly Victorian... for example the ceiling heights have all been raised so it no longer has that cottage-y feel ☹️
There is a fabulous, small walled garden leading straight off the house and beyond that larger, partly walled gardens. For me, the cottage gardens are the best feature although the way they look now is a result of our labours, because before we purchased the property the outside space was a rambling mess of weeds/overgrown hedging 🙄
Inside we are gradually restoring some character (fireplaces, panelling) and outside too (eg, replacing the inappropriate windows), but unfortunately in the 1990s a previous owner actually sold the stone tiled roof, replacing it with slate and we don't currently have the funds to restore that 😮
Imho, the garden is as important to the building and ensuring that matches or at least complements the building style is important, so we're creating a kitchen garden, mini orchard, large pond, cottage garden borders etc. That all adds to and enhances the period charm 😊