Downstream some 200 yards from Trevillett Mill, you will come across Trethevy Mill
now in ruins. This was a Corn Mill later used for making blankets, yarn and worsted cloth for hose.
Two small 7 ring Celtic Labyrinth carvings can be found on the cliff face at the rear of the mill ruin. Although local people had been aware
of these carvings for many years, they were only officially recognised in 1946, it is claimed that the carvings date from between 1400 and 1800 BC.
However some experts consider the carvings are fakes and were carved in more recent times.
Whatever the background to the carvings there is a air of mystery around the place, which giving an aura of calm and well being. Every year, many people make a philgrimage to the carvings leaving flowers and other gifts to the ancient gods.