On a trip to Scotland I saw what looked as if they could have been stone wells in the undergrowth at the side of the road. They were circular, about 3 ft in diameter and 3ft high. They were topped by a circular stone about 6" thickness which covered the whole structure. The top lid had a design round the outside and at first it looked a bit like a car tyre. There were 2 of these 'monuments' about 6-8ft apart. They were not in line with the road but at an angle. They had obviously been there for a long time and no doubt before the road had been built. Can anybody please tell me what they were?