Old "dwelling" site on Smith's Hill - Lincoln, MA

Update: I meant "Smith" not "Flint"

As Route 2 passes westward through Lincoln, it crosses a high point on Flint's Hill before diving downhill to where there is a sharp left-hand ninety degree turn at Crosby's Corner. That stretch of road is famous for car accidents. At the high points you are passing some interesting archeology. Fluted points are said to have been found on the left [I am not sure I believe it] during the preliminary survey to determine how to re-route the highway in a less dangerous layout.

It is what is on the right, north of the road as you reach the crest of Flint's hill, that there is an interesting site. It is off of a private driveway but as far as I know this is public land. It was deeded to the town of Lincoln by the original farmer named Flint. Presumably he felt this one little piece of land was important because of the structures on it. Also presumably, there is no record of who lived there or left these "ruins" since they pre-date Flint. [This is my construction from third hand information and quite possibly mostly fantasy.] In that context, I went to look at these tumbled down stone structures several years ago. Typical sights today:They look like traditional colonial foundations. But this one is curious:I am afraid this is not the way I remembered this circular structure. Last time I was here, about 8 years ago, the walls of this structure came up to chest height and there was no entrance. At the time a kind of box attached to the outer side wall was still visible. Was it just my imagination that it looked like this - like a little stone igloo (the box on the side being like the entrance but not actually connecting through to the interior) and with a missing roof? Well it's gone now.

I cannot quite place something like this:
One last picture, showing what seem to be separate rooms tumbled together. What kind of place was this?Was it historic? Someone with scholarly leanings might look into the records which would probably be in Cambridge.

[On a personal note, I am not a big fan of Lincoln. They have conservation land policing that is quite onerous. I have been kicked out of the town twice for arrowhead hunting yet there is no sign that they take much interest in or value their own archeology. They are not aware of the sites I mention: neither the arrowhead sites nor the stone structure sites.]