You know what this could be?

[Dirty Digger Doug]

Found this on the outside edge of a footing that is about 500' long. It is inside a park that runs along a RR track. There used to be large building here. I thinking the building once serviced the RR. There is a copper plate embedded in the concrete. Guessing it was a marker, but for what? Any ideas?

 

[Loquacious_Leo]

Found this on the outside edge of a footing that is about 500' long. It is inside a park that runs along a RR track. There used to be large building here. I thinking the building once serviced the RR. There is a copper plate embedded in the concrete. Guessing it was a marker, but for what? Any ideas?
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I'm new to the whole treasure hunting thing, so take my opinion worth a grain of salt.

That being said, it's quite possibly a marker like how you said. If anything if a line needed maintenance the workers wouldn't have to travel the whole line to find the problem.

But this is a flat out guess, instead of anything educated.

 

[Blackfoot58]

Was it on the north side of the building: north center? Just curious.

 

[Back-of-the-boat]

Possibly a survey marker

 

[Dirty Digger Doug]

West side of footing.

 

[creskol]

Found this on the outside edge of a footing that is about 500' long. It is inside a park that runs along a RR track. There used to be large building here. I thinking the building once serviced the RR. There is a copper plate embedded in the concrete. Guessing it was a marker, but for what? Any ideas?
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My guess would be the benchmark for the building construction.

 

[Gare]

I think it is a survey monument

 

[Gare]

survey monument - Google Search

 

[teleprospector]

I haven't seen any survey section monuments that look like that in Michigan. But you can check what section of land you are in on a county/township map. If you are in section 15 then maybe that's how they did them in that county.
But if it's on private land I think it's related to something there. If it's in the RR R.O.W. my guess is that it's a mile marker 15 and the symbol indicates a single/multiple RR track. Is there an R/W inscribed on the sides of the concrete square not visible in your picture?
Jon