Wittenham Clumps are a pair of wooded chalk hills in the Thames Valley, in the civil parish of Little Wittenham, in the historic county of Berkshire, although since 1974 administered as part of South Oxfordshire district. The higher of the two, Round Hill, is 390 feet above sea-level. The 350-foot Castle Hill is about 380 yards south-east and was the site of an Iron Age hill fort. A third hill, not normally considered one of The Clumps, is Brightwell Barrow, further to the south-east.