The partly Norman parish church at Knowlton, close to the east edge of Cranborne Chase, is one of the very few churches from this period to survive in a ruined state, after abandonment in the late 18th century following a roof collapse, and it is made more unusual, perhaps unique, for its position within the circular embankment from a Neolithic henge. This part of east Dorset was in ancient times the site of extensive habitation, as shown by many other earthworks including henges, ditches, banks and burial mounds - over 50 have been identified within a few miles, though most are now only barely visible because of ploughing.
The henge and adjacent earthworks date from around 2500 BC and were presumably deserted for many centuries before the settlement at Knowlton was established, prior to the Norman conquest. The church was built in the 12th century to serve the village - which at this time was situated a few hundred yards northwest, extending nearly half a mile along the banks of the River Allen - and it was modified on two main occasions, by addition of a tower in the 15th century, and of the north aisle at the start of the 18th century. Sometime in the Middle Ages the original settlement was abandoned, perhaps due to the Black Death, and relocated to the southeast; it now consists of little more than one farm, also situated within the banks of a henge.
The church has an attractive appearance, constructed of light-coloured stone (heathstone and greensand) incorporating much flint, and most walls are still substantial. The site is free to access and open at all times.
A parking area in front of the field containing the church has space for a few vehicles - along Lumber Lane, just off the B3078, between Cranborne and Stainbridge. Remnants of the other visible henge (the 'Southern Circle'), an approximately oval structure 800 feet across, can be seen around the road junction, either side of Knowlton Farm. Church Henge is more evenly circular, around 300 feet in diameter, and its grassy banks still rise over ten feet above the inner enclosure. The church lies at the centre, and is orientated west to east; it has a square tower at the west end, a nave at the centre and a chancel to the east, about half the size of the nave. A porch gave access from the south, while to the north was a short aisle, probably with a chantry chapel at the east end. Most of the walls of the aisle and porch are reduced to foundations. The Norman origin of the church is demonstrated by two semicircular arches characteristic of this period, one along the north side of the nave, the other between the nave and chancel.