Settlement in the valley began prior the Late Iron Age period. The upper Bulbourne Valley was rich in timber and iron ore. In the late Iron Age, a area around Northchurch was a major iron production centre (considered to be one of the most important late Iron Age and Roman industrial areas in England). Water was drawn from 14 well shafts close to the river at Cow Roast, where a Roman town grew up between the river and the Roman engineered, Akeman Street (which had been a pre-existing route from St Albans ("Verulamium") to Cirencester ("Corinium")) Iron production ceased at the end of the Roman period. There were Roman villas in Northchurch, Berkhamsted and Boxmoor.