 Patterns of settlement varied from decentralised to urban.The popular stereotype of non-urbanised societies settled in hillforts and duns, drawn from Britain and Ireland (there are about 3,000 hill forts known in Britain) contrasts with the urban settlements present in the core Hallstatt and La Tène areas, with the many significant "oppida" of Gaul late in the first millennium BC, and with the towns of Gallia Cisalpina.Slavery, as practised by the Celts, was very likely similar to the better documented practice in ancient Greece and Rome.