When I made a visit to the Trevethy Quoit in Cornwall, near to where I live, I also went on to the village of St.Cleer and it's Holy Well, as per the photos. Though not as impressive, or as ancient as the Quoit, it still goes back to the 15th century when it was used as a magical 'bowsening' pool. So called mad people would be dunked into the waters to cure their insanity.
Well I say the 15th century but it was knocked down during the English Civil War, 1642–1651. This was at the time of Prince Charles I losing his head - by way of execution that is. The Cornish granite stones remained in place and it was said that if any of them were ever removed or stolen they would find their own way back at night - creepy! In the mid 1800s the jigsaw that was the Holy Well was put together again, as it remains today.
Next to the well is an ancient 7 foot cross. There are variations as to whom the St Cleer Holy Well is dedicated. One version is that it is to St Clare, a 12th century disciple of St. Francis. Others argue that it is to St Clarus, a 9th century Benedictine monk. He landed himself in a bit of bother when a noblewoman made romantic advances to him, which he turned down - so he ended up being beheaded.
It's not known who the monk like figure is in the niche at the front of the well house, as photo below.
The Cornish Mystery Of Trevethy Quoit
The Cornish Mystery Of The Men-an-Tol Stones
In Search Of The Birth Of Spirits At Eden