Maybe so, Vickie, your patio might be where an old root cellar was. Sometimes the old ones cave and there will be an indention in the area, but if left alone, and if roots were left there, things will usually find a way to grow. But most of the time there will still be a mound and often the sign of a door.
I'll bet the man did enjoy touring his old house. Nostalgia is usually pleasant.
