Cawfields is a spot where Hadrian's Wall shows its best side. The Wall runs along the top of the Whin Sill, a hard volcanic dolerite ridge, and at Cawfields it follows a steep edge above a flooded quarry, with a milecastle, number 42, sitting in a dip and clear stone steps in its entrance. The quarry was cut into the crag in the nineteenth century, and the lake it left is a popular picnic spot. The temporary camp of the label lies nearby, a faint earthwork from the days of marching armies. It is not much to look at, so use it as an excuse to walk the Wall instead.
Whin Sill is a sheet of rock that was forced between layers of sedimentary rock about 295 million years ago, and it forms the ridge that carries not just the Wall but Bamburgh Castle and the Farne Islands on the coast. At Cawfields the dark rock breaks into columns, and its steep north face made a natural barrier that the Romans were wise to use. Walk up to the crest and you see the Wall disappearing in both directions, a stone ribbon over green hills, and the Pennines to the south. On a clear day, the effect is hard to forget.
Riding here means the Military Road, the B6318, which hugs the line of the Wall between Haltwhistle and Housesteads and gives a roller-coaster ride of dips and crests. It is a fast road with limited visibility on some crests, so keep your speed down, particularly in summer when walkers and cars cross it. Cattle and sheep graze beside it, and in winter it can be icy. A car park near Cawfields charges a fee and has toilets, and there is usually a small van selling coffee in high season.
Haltwhistle, under three kilometres away, has fuel and shops, and Hexham is the larger town about twenty-two kilometres east. Bring a waterproof, because the exposed ridge makes its own weather, and in a bad wind you will want to turn back before you reach the crest. Dusk brings out the barn owls over the fields, and the stone of the Wall turns golden. The Twice Brewed pub and the Vindolanda site, a little further east, make a good end to the day.