I am from the town where the houses were filmed

The houses have not changed since the film was made, a few driveways and stone walls are long gone, along with the garden statuary. It's strange to see an area that you know from your childhood in a movie and even stranger to see that it hasn't really changed that much in 50+ years! The other change I noticed were highway signs, they are larger now. Does anyone know where the horse back riding scenes were filmed? The countryside looks so much like the banks on the Nashua River that isn't that far from those mansions.