Where I was
I live in an old house. Not old like built last century, but old "was built before the Civil War" old. The walls are not structured how you would think, the duct work is not how you would think, the electrical is not how you would think, the plumbing is mostly how you would think. Suffice it to say, everything in the house is an addon. Even the bathroom, because most houses just had an outhouse and not a toilet inside back then.