This is part of the Rollrights, a Neolithic stone circle in the Cotswold Hills, England.
On April Fool's Day two or three years ago (I forget exactly when) somebody senselessly and deliberately daubed almost every stone with yellow paint.
The Rollright Trust appealed to the National Trust for help in removing the paint, as it wasn't possible to do so easily without destroying the lichen colonies on the stones.
To date, there is still considerable residue of paint left.
A stupid and pointless act of vandalism has spoiled people's enjoyment of this ancient monument, and will probably do so for some time into the future.
What sort of world are we living in?!