In their early days, New England towns built enclosures like this to constrain livestock that had been captured on the lam and impounded. These days such sites are altogether nostalgic.
TOWN POUND
You never know what we'll churn up in cleaning a stall
Jnana's Red Barn 
We have a couple of these in our town too. At first I thought it was for their lost dogs and thought, gee that won’t keep them in… LOL
Reblogged this on Oyia Brown.
In the hill top in my town
These were built
For some water harvesting purposes
May be in the past people came to these places to meditate
Like buddhists
As well we, too, may today …
At first I thought “town pond” because the stone wall reminded me so much of a pond in the woods near where I grew up in CT. If my hometown had pounds like this I am sure they were long gone by then. But in the woods where old farms once stood there were a number of water controlling structures over springs made from the local rocks held together with cement.
We are in Exeter NH and there are a few of these around we have seen in our travels, I always wondered what they were! Now we know thanks to your post LOL.