Could this be a one room School house?

I thought it was originally a school however it is on a gravel lane more akin to a driveway vs a road (and all of the Greenville Township one room schools were on or very close to a paved road) and it does not resemble the two one-room schools (Greenville Township #15/Hall School to the south and #18/Cedar Point School to the east) that are within a mile of the photos before and after this one. I determined the location via a 1973 USGS map showing a house on a gravel lane behind this house: https://vintageaerial.com/photos/ohio...

I love these kinds of quests. Gozman, it does appear to be a road today, Livingston Rd. There is a Livingtson Rd listed in the 1969 Darke County rural directory but it is not this one (which is in the city limits and might not be listed). Backtracking by looking at Martindale Rd it only reads "lane intersects south" at this location. Perhaps "Livingston" is a more modern name for the lane. I did find an excellent close look at this house on the ODOT aerial maps in the 1950s. I looked at several county atlases from 1910 and 1888. No school is listed here, only the ones you already mentioned.

The house is bigger than a one room school as it has another section behind the one you can see in the photo. You can just see the roof by the old cars.

This lane led to a landfill just south of this house and south of the railroad at the time of this photo. I had been down it a few times with my father in th elate 1960's. Most likely this one was paved & named with or soon after the US-127 bypass opened about 50 yards west of it in 1969. Martindale is old OH-571 which was moved just to the north when a new bridge was constructed for it over the Bridge Creek and then became an orphaned 1/4 mile segment when the old bridge to the east was condemned and the new bypass cut it off from US-36 to the west.

The bridge over Bridge Creek, hmm. Looking on the older aerials at Historic Aerials I can see exactly the way you described it. There was a house south of the tracks before the landfill. Is this your home county? I was raised in Lorain County. You can just make out the cabin we lived in when I was born here:

https://vintageaerial.com/photos/ohio...

I lived about a mile north of here when the photo above was taken. Moved to the house here a couple years later: https://vintageaerial.com/photos/ohio...