Help with ID of Pipe/Hole in Basement Floor

Hello - I wanted to see if anyone could help ID something found in the basement of a home I'm looking to purchase. Over by one of the walls, there is a square hole in the poured concrete basement floor - the corners have what looks like anchors for something to be screwed or bolted on to the top. The hole itself is about 4 inches deep and concrete bottom. In the center of the hole, there's a 3-inch metal pipe sticking up with a metal cap that's been bolted on to the top of it. The house is built in probably the 1940's or 1950's (cinder block walls), has an underground drain/sewer and no sump system. This is a very rural area but in town so there is currently city sewer and city water.

The home inspector looked at it and couldn't figure it out but he had a couple guesses:
1. Underground fuel storage tank (I did research and it seems like most of these were either free-standing in the basement or buried beside the home. I've never seen an example of one buried under the concrete slab. Plus there's a single 3-inch pipe sticking up and not 2)
2. Capped off well
3. Drain clean out

Any suggestions or hints would be appreciated. Thanks in advance - here's a photo - I know it may be small:

Can you get a better photo. Zoomed in and it's very blurry.

Here's a higher res photo - you can definitely see the shape of the cap - it's bolted down to the top of the pipe on all 4 corners.

My guess would be a well. But could be wrong.

looks like a floor drain cover....??????

Unless you pull that cap it is all just a guessing game. Is it anywhere near where the sewer enters the house. Is there any underground sanitary piping near that area. If no sanitary anywhere near it I will go with an old well system.

Just talked to our head plumber at work and he's saying it has something to do with electrical. He's thinking it's an old electrical box.

Thanks for the help all. Have had several people come in with the old well idea and it makes sesnse. This home was likely in an area that was all well before the municipality added water later on. Just never seen a well head under the foundation before.