Most of the remaining speakers of Celtic languages live in the British Isles, in Wales, northwest Scotland and Ireland. Until the Anglo-Saxons began settling in England in the 5^th century, Celts were spread throughout Britain, but today almost all that remains of these Celts is place-names derived from early Celtic. Almost all, because we know from classical writers of the 1^st century BC that the Celts of Gaul venerated watery places like lakes and rivers and deposited precious objects there. This book traces the Celtic use of watery places from the Late Bronze Age, around 1000 BC, to the Roman period (43 AD - 410 AD). Christian Celts did not deposit precious objects in rivers and lakes, but they did build monasteries on islands, especially in Wales and southern Scotland. Meanwhile the Scots, following a tradition established in the Iron Age, buit crannogs, dwellings on artificial islands, in some of the many lochs of Scotland. From the 7^th century the Anglo-Saxons also established monasteries on islands or near watery places. In 1066 the Anglo-Saxons were replaced by the Normans and holy wells proliferated, perhaps inspired by models in France.