On the South Downs in the north-west corner of Brighton

The Dyke is only a few feet wide at its base, and is the largest dry valley in Britain, having not been formed by a river.
Folklore says it got its name when the Devil was upset at the way churches were being springing up all over Sussex - one of the last counties to give up paganism. To teach the Christians a lesson, he decided to dig right through the South Downs and let the sea flood Sussex in a single night and drown the new converts. Starting inland near the village of Poynings, the Devil attacked his task with gusto. His digging made such a noise that he disturbed an old woman, who held up a candle and knocked her cockerel off his perch. The Devil heard the cockerel crowing, saw the light which he mistook for the sun rising, and fled the scene before he could finish the job. Some say that as he fled out over the English Channel towards France, a great lump of earth fell from his cloven hoof, which became the Isle of Wight.