Wittenham Clumps above Dorchester are the age-old landmark of the Oxfordshire/Berkshire Thames; they sit atop the Iron Age hillfort known as Castle Hill. An extensive survey of the hill tops and the landscape around with geophysical mapping and selective excavation shows that there was a late Bronze Age defensive enclosure of about 1000BC before the hillfort; contemporary settlements were located outside both enclosures. In the Roman period there was a villa-style building outside the hillfort; and in the late Roman period the hilltop was re-occupied and the defences renewed. Extensive reporting of all aspects of the survey and excavations with lots of colour.