Location: 42.62066, -83.20884, at 3995 South Blvd, Troy, MI (southeast corner of Adams and South Blvd).
Stone School (Fractional School District 10) was built in 1858, and became a private home in 1933. It has 20-inch-thick stone walls and 3 windows on each side. The front has a centered door and a window on both sides of it, and the back has a centered door. A wishing well is in front of the building. The city of Troy now owns the building since its last owners willed it to the city, and is deciding what needs to fixed, restored and improved in order to keep this schoolhouse for posterity. In 1985 it was slated to receive a historical marker, but that apparantly never happened. I didn't come across this schoolhouse in any of my research, and thank the kind Katie Miles who emailed me to tell me of this schoolhouse.
