The hillfort on Castle Hill, earliest earthworks date to the late Bronze Age. More banks and ditches were added during the early Iron Age
Wittenham Clumps is the name for a group of small hills in the otherwise flat Thames Valley, Oxfordshire. Mostly grassed, but are wooded at the top with ancient beech trees giving them a distinctive and prominent appearance. The area is a popular beauty spot, with a car park and paths for access on foot.
Strictly speaking, the name Wittenham Clumps, or simply The Clumps, refers to the wooded summits of these hills, which are themselves more properly referred to as the Sinodun Hills, the name Sinodun deriving from Celtic, Seno-Dunum, meaning 'Old Fort'. Other lesser-used and more colloquial names for the Clumps include the Berkshire Bubs and Mother Dunch's Buttocks (after a local Lady of the Manor named Dunch). The two main hills are called Castle Hill and Round Hill.