Ever since the beginning, I've been making numerous interesting discoveries about the original layout of the house. The house has been changed several times, but the basic layout is about the same. The first, obvious change is that the master bedroom is made up of 2 former bedrooms. These were originally separated by two VERY NARROW closets. These were about 16" deep (as evidenced by the shadow lines on the floors and in the drywall). The current closet used to be the hallway with the door leading into the second bedroom.
On the opposite side of the house, the laundry room and "L shaped room" in front used to be two mirror-image bedrooms. The door in the laundry room that leads down to the garage, and outside actually used to be a window.
When the upstairs was turned into an apartment, the laundry room was made into a combination kitchen/laundry room. The closets that divided the room were also modified into an archway. A hole was very roughly knocked-into the chimney to vent the stove or heater.
Here is the archway turned into an arch with two cubby cabinets on each side:
The poorly done hole in the chimney:
And the shadow of the two closets in the master bedroom:
On the main floor, I've concluded that the wall against the stairs (hallway side) is a later addition, and the wall that makes up the front room (computer room/office) is also a later addition. The rest of the main floor appears to be original.
The only part of the house I can't really be 100% sure about is the exact location of the stairs. The stairs currently pass partially into the door to the living room. I'm sure it was NOT like this originally. The door, though, has definitely not been moved. To add to this puzzle, the ceiling above this shows signs that the crown moulding originally went around the top of the door, across the stair opening, and back down the length of the hallway to the kitchen, which seems to indicate that the stair wall is original (but the studs in it don't match the old studs in the rest of the house....)