Finding Physical Evidence: Old Kitchen?!?

Researching the history of your house must undoubtedly involve a thorough inspection of the inside and outside of your home with an eye trained towards unearthing clues. In previous posts, I have already touched on a few physical clues, such as those that tip off a previous rear addition, and the covering over of an exterior window in one of the bathrooms.

A few short months after moving into the house, before I got heavily involved in researching its history, I was in the basement trying to get a better understanding of all the piping hanging from the first floor joists above. Over by the stairs leading to the first floor was a pair of gate valves, on a set of side-by-side water supply pipes, with some duct tape wrapped around each. There was something scribbled onto the duct tape in black magic marker:

Copper water pipes, with old gate valves shutting off supply to the mysterious "Old Kitchen"

"Old Kitchen"?!? What does that mean? Houses do tend to undergo many physical alterations and changes over time, but relocating the whole kitchen would be one of the larger undertakings on the list. My immediate thought, and one that persisted for a bit, was that the kitchen of the house was at one time located in what is now the rear bedroom. I made this inferrence due to further inspection of the basement piping. Following the two water supply pipes with the duct tape tag, they turn at the foundation wall, heading along it for a few feet before penetrating through the foundation wall into the unexcavated crawl space. In addition, a sanitary drainage line pokes through this wall as well, right around the same location. These penetrations occur more or less underneath the demising wall between our living room and the rear third bedroom. Furthermore, this wall between the two rooms on the main level is extra-thick. These are all very strong indications that the wall is a former plumbing wall, with that bedroom being a former kitchen.

Copper pipes now oxidized where they run along the foundation wall. Sanitary drain pipe coming from the "Old Kitchen" is right below that.

However, that location as a kitchen doesn't make a lot of sense looking at the main floor plan. Sure, before modern homes valued the kitchen as a central feature of the house, kitchens were often located at the rear, more out of the way. But in this case, we have always been pretty certain that this location was part of an addition, constructed at some point after the original main house. Did the kitchen originally exist where it does now, in the center of the house, then get moved to the addition, then get moved again by my previous owners after 2001 (based only on the knowledge that they did a lot of work to the house)? That theory sounds a bit far-fetched and didn't make much more sense than the original theory.

Sketch of the main floor (L) and basement (R) plans. The presumed addition is the Living Room and Bedroom at top of the page, with unexcavated space at Basement level. Possible location of "Old Kitchen" is the rear bedroom-- the piping punches through the foundation wall at the location of the staircase in upper right corner of plan.

Still, someone in the past left this duct tape label over the abandoned plumbing valves, and I figured this most likely to be the previous owner of 2001-14. Surely the tape couldn't be more than 15 years old, right? I ran this by him, and he indicated that the kitchen was always where it was as far as he knew, but he had also had similar inklings of layout changes having occurred before his ownership. So it does seem that this duct tape was there prior to 2001 after all.

Then, however, at some point thereafter I had an epiphany...