Henge Enclosure, Conquer Barrow and Barrow Cemetery


Heritage Category:
Scheduled Monument
List Entry Number:
Date first listed:
Date of most recent amendment:
Statutory Address:
Mount Pleasant, Dorchester, Dorset, DT1 2AN


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Statutory Address:
Mount Pleasant, Dorchester, Dorset, DT1 2AN

The building or site itself may lie within the boundary of more than one authority.

Dorset (Unitary Authority)
Dorset (Unitary Authority)
West Stafford
National Grid Reference:


The monument includes a Late Neolithic henge enclosure; Conquer Barrow, a substantial earthwork which probably dates initially to the Late Neolithic period; and a number of later prehistoric round barrows which variously survive as upstanding earthworks and as ring ditches visible as cropmarks on aerial photographs.

Reasons for Designation

The henge enclosure, Conquer Barrow and the barrow cemetery at Mount Pleasant are scheduled for the following principal reasons:

* Rarity: henges are one of the relatively few types of monuments which characterise the later Neolithic period and this example is one of only four large henge enclosures known nationally. Conquer Barrow is an enigmatic monument that is considered likely to have had significant role at this ceremonial site; * Potential: despite plough-levelling, they are considered to retain important archaeological information and environmental evidence relating to prehistoric ritual and funerary activities and the landscape in which they were constructed; * Documentation (Archaeological): they have been well-documented through aerial photography, geophysical survey and excavation, which enhance our knowledge of these monuments; * Group value: located on Alington Ridge, an area with a dense concentration of Neolithic and Bronze Age funerary and ceremonial monuments, a study of which will contribute valuable information about the continuity of land use and the importance of this landscape to prehistoric communities.


The Dorchester area contains an extensive range of buried and upstanding Neolithic funerary and ceremonial monuments, including the henge enclosure at Mount Pleasant. Strictly speaking, henges are circular monuments consisting of an earthwork bank and internal ditch and sometimes associated with stone or timber circles. One, two or four entrances provided access to the interior, which may contain a variety of features including timber or stone circles, post or pit alignments, pits, burials or central mounds. Henges are generally interpreted as arenas for various ritual practice or meetings, and most dated examples were constructed in the Late Neolithic, between 2800 and 2200 BC.

The large henge enclosure at Mount Pleasant is situated on top of the highest point of the Alington Ridge to the south-east of Dorchester, close to the confluence of the Rivers Frome and South Winterborne. In the late C19 it was described as ‘Vespasian’s Camp (Warne, 1872). By the 1930s it was considered to be a possible henge, however, it was not until it was the subject of archaeological investigations between 1969 and 1971 (Wainwright, 1979) that the site was formally recognised as a henge enclosure. It dates from the Late Neolithic period, erected probably prior to 2500 BC, although there is evidence of earlier Neolithic occupation on the site. In its initial phase the henge comprised a large enclosure, bounded by a substantial ditch and an outer bank, although evidence from excavation and aerial photographs suggests that the ditch may have been preceded by a circuit marked out with pits. The henge underwent several phases of modification over the centuries. A continuous timber palisade running concentric to the inner ditch of the henge enclosure was added around 2000 BC, and a circular structure of five broadly-concentric rings of timber posts within a pennanular ditch (known as Site IV) was erected in the south-western part of the henge about the same time. This structure appears to have been replaced (Wainwright, 1979) by a structure of sarsen stones in around 1700 BC, but the precise sequence of events has not been fully established. The excavations also demonstrated that the west entrance was substantially narrowed sometime before 1800 BC. The palisade appears to have been deliberately destroyed by fire and dismantling at a later unknown date. Large quantities of Early Bronze Age pottery was recovered from the upper fills of the enclosure ditch and the palisade trench, as well as Middle Bronze Age pottery from the main enclosure ditch, thus indicating that the henge remained in use during the Bronze Age. Occupation during the first millennium BC appears to have been sporadic; the sarsen structure was destroyed around this time. Evidence of Roman and Anglo-Saxon activity, the latter including two graves and a round house, has also been found.

At the western edge of the henge enclosure is a substantial earth mound which is described on the First Edition Ordnance Survey map of 1889 as Conquer Barrow. It has been the subject of only minimal investigations. During Wainwright’s excavations at Mount Pleasant small sections of the ditch that encircles the mound were examined, but did not provide any conclusive evidence for a stratigraphic relationship between Conquer Barrow and the henge. Little dateable evidence was recovered, but did include an antler pick and several pottery sherds, including a Bronze Age sherd. The antler was radiocarbon dated to 2870-2480cal BC, but at the time it was considered to have derived from an earlier context rather than being directly associated with Conquer Barrow. Wainwright concluded that the mound was constructed later than the henge and was a Bronze Age barrow, albeit larger than normal. Since the 1970s there has been much debate (Woodward, 1991; Barber et al, 2010) regarding the exact relationship between Conquer Barrow and the henge. In 1994 it was suggested (Sparey-Green) that stratigraphically the barrow’s ditch might pre-date the henge ditch. A more recent interpretation (Barber) based on analysis of aerial photographs has suggested that Conquer Barrow, or at least its surrounding ditch may have been constructed either prior to, or around the same time as the initial construction of the henge and that it formed part of the monumental complex at Mount Pleasant (Davies et all, 2002). On the evidence available it cannot be established with any certainty whether the mound in its present form is contemporary with the encircling ditch or if it is a later feature.

To the south-east of the henge are two prehistoric barrows, one of which is survives as an earthwork. Recent analysis of aerial photographs has identified a number of previously unrecognised circular cropmark features in the immediate area, though some of them have been photographed previously, which are considered to be plough-levelled round barrows. Together with the two already known about, they are considered to be part of a Bronze Age barrow cemetery. None of these features has been the subject of archaeological investigations, but the excavation of a number of other barrows to the east and south-east of Dorchester town centre has indicated that those at Mount Pleasant may form part of a much larger linear cemetery which extended along the Alington Ridge.


PRINCIPAL ELEMENTS: the monument includes the earthwork and buried remains of a Late Neolithic henge enclosure at Mount Pleasant, situated on the west-east axis of the Alington Ridge. Immediately to the west is Conquer Barrow, a substantial earthwork which probably dates initially to the Late Neolithic period. To the south-west and south-east are a number of later prehistoric round barrows which variously survive as upstanding earthworks and as ring ditches that are visible as cropmarks on aerial photographs.

DESCRIPTION: the monument is evident as a complex series of cropmarks and earthworks in an area of approximately 13 hectares. The henge was subject to geophysical survey and excavation in 1969-1971 and also has good aerial photographic coverage. A watching brief was carried out in one part of the site in 1986. These investigations collectively provide considerable information about the form and function of the monument.

Excavation of the henge has indicated that it comprises a large, roughly D-shaped enclosure defined by a bank and an internal ditch which enclose an area some 370m from west to east and 340m north to south. The chalk rubble bank was originally some 4m high and its width varied between 16m and 23m Although the site has been under plough for centuries, it survives as a slight earthwork along its south-eastern sector, although this may be due to a possible later heightening of this section of bank. All but the north and north-west sections of the bank are visible on aerial photographs and on LiDAR (remote sensing); it is possible that the northernmost section may have been truncated by the construction of the railway cutting. The width of the internal ditch varies between 9m and 17m wide and its depth is irregular. Although it cannot be traced on the ground, almost its entire circuit is visible as cropmarks. Aerial photographs taken in 2004 have provided evidence for a berm between the bank and ditch and also for an external ditch on the north, east and south-east sides of the enclosure; however it is unclear whether this ditch is present around the whole circuit of the henge.

There are a number of entrances into the enclosure, to the west, east, south-east and north, and a fifth entrance in the south-western section has been identified on aerial photographs taken in the 1990s. The 1970-1971 excavation demonstrated that the west entrance had been narrowed in about 1800 BC by extending the adjacent ditch terminals, while two rows of large pits within the south-western entrance, visible on aerial photographs, seem to indicate that this entrance may also have been narrowed or partly blocked at some time. A foundation trench for a palisade running within and parallel to the enclosure ditch was also partly excavated in 1970-1971 and found to contain post holes for closely-set, large oak timbers that probably stood some 6m high. Narrow entrances to the north and east were identified through the palisade which aligned with the respective entrances in the enclosure bank. The excavation also uncovered evidence to indicate that some sections of the timber palisade were destroyed by fire, while elsewhere its posts were removed or left to decay in-situ. To the north-east of the henge is a substantial linear feature which appears as a cropmark on aerial photographs, but can also be discerned as a wide, shallow depression on the ground. It is at least 200m in length and is orientated south-west to north-east, running close to, but not aligned with, the east entrance. It has been suggested (Barber, 2005) that it may be some form of approach to the henge, but it has not been subject to archaeological investigation.

Within the south-western area of the enclosure is the large circular feature known as 'Site IV' which has been dated to around 2000 BC. The excavation provided evidence that it comprised a penannular ditch, some 43m in diameter, 2.5m wide and 2m deep with an entrance on its north side which encircled five broadly concentric rings of posts holes where large wooden posts once stood. These were laid out around central aisles which were aligned north to south and east to west respectively, dividing the rings into quadrants. A series of larger pits representing the remains of a rectangular structure of sarsens were also found, along with evidence for a number of outlying pits and monoliths. Site IV’s ditch remains clearly visible on aerial photographs taken in the years post-excavation.

The pottery recovered during the excavation of the henge was primarily Late Neolithic Grooved Ware, but Wessex/Middle Rhine, plain Neolithic bowl forms and Beaker Ware were also present, as well as later prehistoric and Romano-British pottery. Flint and chalk artefacts, antler picks, human remains, animal bone, a Bronze Age axe and two Anglo-Saxon inhumation graves were also recovered.

Conquer Barrow is situated immediately to the west of the henge. Its earthen mound rises approximately 8m above the surrounding ground surface and is around 30m in diameter at its base, rising to a flat summit, some 7m in diameter. Archaeological investigations, including augering and limited excavation, in 1970 demonstrated that the mound is surrounded by a circular, flat-bottomed ditch, some 7m wide and 3m deep, which is interrupted by at least two causeways. A ditch terminal and small section of ditch were briefly examined in 1970-1971, but little dateable evidence was recovered; an antler pick, radiocarbon dated to 2880-2480cal BC, was found either in the primary fills or the base of the ditch, and some fragments of pottery, including a Bronze Age sherd, a Beaker sherd and some of Iron Age date. Although it is not visible on the surface, the ditch is considered to survive as a buried feature.

Some 370m south-east of the henge is a later prehistoric round barrow (SY7149989701) which survives as a circular earthwork mound some 16m in diameter and 1.5m high. The surrounding quarry ditch, from which material was excavated during the construction of the mound, is no longer visible at ground level or on aerial photographs, but it is likely to survive as a buried feature. In addition, eight cropmark ring ditches which are considered to represent the remains of plough-levelled barrows are visible on aerial photographs to the west and north-west of the upstanding barrow. Collectively they form three discrete groups: two parallel groups of three and four barrows which are orientated north-west to south-east, and two further ring ditches slightly to the north which are located between the parallel groups. The ring ditches vary in size, with internal diameters ranging from 13m up to 32m. The one immediately north-west of the upstanding barrow was described as a ploughed-down mound in 1979, but has since been levelled by cultivation. In 1986 the area in which the northernmost ring ditch is situated was examined during a watching brief in advance of the construction of a water pipeline to the south and south-east of the henge. It revealed some features associated with burning on either side of the location of the ring ditch and a small collection of lithic finds. However, nothing firmly identifiable as the ring ditch appears to have been identified. The area between these groups of ring ditches regularly produces ‘natural’ cropmarks, which may possibly mask the presence of other archaeological features. The cropmark of a further possible ring ditch has also been identified approximately 140m south-east of Conquer Barrow, but it is a relatively small feature that is isolated from the rest of the group and is not included in the scheduling.

EXTENT OF SCHEDULING: the scheduled area, which comprises four separate areas, includes the known extent of the henge enclosure, the upstanding earthwork known as Conquer Barrow, and the groups of ring ditches and one upstanding bowl barrow. A 2m margin has been included for the support and protection of the monument on all sides, except to the north where the monument boundary follows the line of the railway cutting.

EXCLUSIONS: all concrete and wooden fence posts, fencing, garden walls, sheds and decking and retaining walls are excluded from the scheduling, but the ground beneath these features, however, is included.


The contents of this record have been generated from a legacy data system.

Legacy System number:
DO 624
Legacy System:


Books and journals
Wainwright, G, Mount Pleasant, Dorset: Excavations 1970-71. Report of the Research Committee of the Society of Antiquaries of London, 37, (1979)
Barber, M, 'Mount Pleasant, Dorchester: Cropmarks Old and New' in Past: the Newsletter of the Prehistoric Society, , Vol. 49, (April 2005), 5-7
Barber, M, 'Mount Pleasant from the Air, Cropmarks old and new at the henge enclosure near Dorchester, Dorset' in Proceedings of the Dorset Natural History and Archaeological Society, , Vol. 126, (2004), 7-14
Davies, SM, Bellamy, PS, Heaton, MJ, Woodward, PJ, 'Excavations at Allington Avenue, Fordington, Dorchester 1984-87' in Dorset Natural History and Archaeological Society Monograph Series , , Vol. 15, (2002), 186-194
Sparey-Green, C, 'Observations on the Site of the ‘Two Barrows’, Fordington Farm, Dorchester; with a Note on the ‘Conquer Barrow’' in Proceedings of the Dorset Natural History and Archaeological Society, , Vol. 116, (1994), 45-54
Barber, M, Mount Pleasant, Dorset. A Survey of the Neolithic ‘Henge Enclosure’ and Associated Features, Historic England Research Report Series no. 70-2014
Barber, M, Winton, H, Stoertz, C, Carpenter, E and Martin, L, 2010, The Brood of Silbury? A Remote Look at Some Other Sizeable Wessex Mounds in J Leary & D Field (eds), Round Mounds and Monumentality in the British Neolithic and Beyond, 153-173


This monument is scheduled under the Ancient Monuments and Archaeological Areas Act 1979 as amended as it appears to the Secretary of State to be of national importance. This entry is a copy, the original is held by the Department for Digital, Culture, Media and Sport.

End of official listing

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