Uffington Castle, atop White Horse Hill, is a superbly sited hill fort that dates from around 700 BC. All that’s visible today is the vast grassed-over earthen wall that once surrounded it, enclosing large, long-vanished wooden huts. This is Oxfordshire’s highest point (262m), so views stretch in every direction.
To reach it, walk half a mile east from the hill’s car park.