When you live in a 200-year-old house, you would do well to give it a thorough inspection every few years. Rap on the walls, pull down some old wallpaper, climb into the attic, and get down into the crawl space. Check the roofing, check the exterior walls, check the foundation. You are looking for signs of rot: decay, mold, insects, rodents, or just plain aging. With luck, you find one or two small problems, you patch them up, and all is well. Unfortunately, sometimes all is not well. Sometimes, you find signs of major and irreparable decay. In those cases, and as painful as it may be, you must be prepared to tear the house down and start anew. Anything less would be a lost cause, an act of utter futility.