The wooden steps (and the door) on the right side, as well as that wooden thingie with two windows just above it, seem to be later additions to the house. So I imagine the owner had to rent out some space, to pay for the upkeep of that extravagant dwelling, and added some rooms independent from the rest of the house.
That tower on top also looks like it was built long after the original building. You probably have a nice view from up there, which is why it was added, I presume.
(On the other hand, I can also imagine the inside being just *one* big room )
If you dont't mind sharing this info, I'd like to ask if you have these kinds of pictures worked out in your head before you start, or if they sort of "evolve" during the drawing stage?