From around 600BC, Iron Age became the predominant technology, being harder than bronze and easy to manipulate into many tools. In Worcestershire, the most visible reminder of the period is hill forts. There around ten or twelve extant, including British Camp, Wychbury Hill and Hanbury. The full list may include east of the Severn Bredon Hill, Conderton Camp, and Headless Cross; and west of the Severn, Woodbury Hill, Berrow Hill Camp and Gadbury Bank