H M Prison Dartmoor: Polygonal buildings, former officers' mess and former steward's house, now admin building and visits building

Two polygonal buildings, with canted ends to the east, and squared blocks to the west. These date from the first phase of building, 1806-9, to a design by Daniel Alexander, but have been added to and altered since, with a much altered mid-C19 block to the north of the northern building, and a 1909 block to the south of the southern building.

MATERIALS: coursed granite rubble, with replacement ashlar window surrounds, and replacement frames. The roofs are metal; the roofs to the polygonal sections are pyramidal, with finials.

PLAN: the polygonal buildings stand to north and south of the entrance to the former marketplace, with canted ends facing into the former marketplace to the east. They extend westwards, ending in squared west ends. Both buildings have later attached structures: the southern building has the large block built as an officer’s mess to the south, and the northern building has a much altered section to the north.

EXTERIOR: the two polygonal buildings stand on granite plinths. The polygonal sections have large triangular-headed windows to the first floor, overlooking the former marketplace, probably reflecting their original form. The other windows are small. The southern building is entered from the north-east and from the south; the northern building has blocked openings to the south-facing elevation, and a new secure entrance in a lean-to addition against the west wall of the former steward’s house. There is another late-C20 extension projecting westwards from the north end of this building. The former officer’s mess to the south is a two-storey building with four pairs of basket-arched windows with granite surrounds, and an attached central chimney.

INTERIORS: the interior of the northern building has been opened out, with no division between the polygonal part and northern range; it is thought that few historic features, though the bottoms of roof timbers appear to be visible in the polygonal part. The interior of the southern building was not inspected.