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An Sean Dun, Mull

Broch (Iron Age)(Possible), Dun (Period Unassigned)

Site Name An Sean Dun, Mull

Classification Broch (Iron Age)(Possible), Dun (Period Unassigned)

Alternative Name(s) Baliacrach

Canmore ID 22079

Site Number NM45NW 3

NGR NM 4310 5624

Datum OSGB36 - NGR


Ordnance Survey licence number AC0000807262. All rights reserved.
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Administrative Areas

  • Council Argyll And Bute
  • Parish Kilninian And Kilmore
  • Former Region Strathclyde
  • Former District Argyll And Bute
  • Former County Argyll

Archaeology Notes

NM45NW 3 4310 5624.

(NM 4310 5624) An Sean Dun (NR)

OS 1:10000 map (1976)

Dun, An Sean Dun: Situated 1.2 km SW of Glengorm Castle, An Sean Dun is one of the best-preserved duns on Mull. It occupies the highest part of a ridge which runs from NNW to SSE, and is protected on the E by a short but sheer rock-face falling about 3.6m to a steep grassy slope; the other approaches are over a series of rocky terraces.

Circular on plan, the dun measures about 9m in diameter within a wall, some 3m thick, faced with large blocks. The circuit of the inner face is complete, and that of the outer face nearly so. The best-preserved stretches of the outer face are on the N, where the wall, incorporating stones up to 1m long, stands to a height of 1 m in three courses.

Behind the inner face on the NW and SSE sides there is a scarcement ledge, which measures 0.35m in width on the SSE and between 0.25m and 0.4m in width on the NW; the scarcement stands about 0.7m above the present ground-level of the interior. A gap in the inner face of the dun wall on the SW, measuring about 1m in width, may be the entrance to a recess or to a stair. An internal wall-face visible on the NNE and S is probably a revetment, similar to those found on a number of sites in Kintyre and Lorn, rather than the remains of a mural gallery.

The entrance to the dun is on the ESE and has been protected by an outwork running from the cliff edge on the E to the dun wall on the S. This outer wall has been more heavily robbed than that of the dun; its outer face stands at best to a height of 0.6m in two rough courses.

The entrance is in line with that of the dun.

RCAHMS 1980, visited 1973; R W Feachem 1963

An Sean Dun, a dun.

Revised at 1:2500 scale.

Visited by OS (JP) 24 April 1972.

Scheduled as An Sean Dun, dun.

Information from Historic Scotland, scheduling document dated 11 November 2003.


Field Visit (8 June 1934)

Broch, An Sean Dun.

One isolated rock northernmost outpost of a ridge 200' OD commanding superb view to Ardnamurchan amd Skye. Summit girt with wall 10 1/2 thick internal diameter 31 1/4 entrance inside 4 1/2 with jambs etc. broken but trave of cell on left. Middle left in wall entrance to ? cell and stair. Very probably a broch.

Visited by VGC 8 June 1934.

NB This note by VGC incorporated into the RCAHMS Emergency Survey transcript and manuscript collections during 1942-3. (RCAHMS GFG 2013).

Field Visit (29 July 1942)

This site was included within the RCAHMS Emergency Survey (1942-3), an unpublished rescue project. Site descriptions, organised by county, vary from short notes to lengthy and full descriptions and are available to view online with contemporary sketches and photographs. The original typescripts, manuscripts, notebooks and photographs can also be consulted in the RCAHMS Search Room.

Information from RCAHMS (GFG) 10 December 2014.

Publication Account (2007)

NM45 1 AN SEAN DUN (‘Balia-chrach’)

NM/4310 5624

This broch, probably ground-galleried, in Kilninian and Kilmore is classified as a dun by the Commission [2]. The site stands in the midst of moorland on a high, sheer rock knoll at the end of a long ridge and with a steep climb up to it most of the way round (visited 4/6/64 and 9/10/89). From the outside it seems to stand only a few courses high but since the scarcement is visible most of the way round, there must be 1.5 - 1.8m (5-6 ft) of inner face below this.


Level 1: the structure is circular and the entrance, full of debris, faces west-north-west. A large lintel at the inner end has fallen in, and the passage narrows at the outer end; the door-frame is probably hidden under the debris. There are no clear signs of guard cells. The whole of the inner wallface can be seen, and much of the outer; in the north the latter stands up to 1m high in three courses and includes some very large stones up to 1m long. The only clear sign of the structure of the wall at ground-level is between 1.30 and 3 o’clock where the inner face of the intramural gallery goes down below scarcement level; thus the broch is probably of the ground-galleried type. There is also the evidence of the doorway at 9 o’clock (below).

Level 2: at 9 o’clock is visible a doorway from the interior, lacking its lintels, and the inner face of a mural gallery is traceable running a few feet clockwise from it; this is presumably the stair door. Its left side can be seen to go 1.5m (5 ft) into the wall so there is presumably no stair-foot guard cell or ground-level gallery at this point. The interior is full of debris but a well- preserved scarcement of the ledge type can be seen to run round the inner wallface; the gallery door is below this so it probably gives access to a ground-level gallery. From about 1.30 to 3 o’clock the inner face of the mural gallery is again visible at scarcement level and this ought to be a first-floor one. The wall stands nearly 60cm (2 ft) higher than the scarcement so its maximum surviving height should be at least 1.8 - 2.4m (6-8 ft).

There are traces of an outer wall close to the broch on the inland side.


The Commission diagnosed the intramural wallface visible on the north-north-east and the south – that is, at 4 and 9 o’clock – as probably a core revetment rather than a hollow gallery and this is doubtless why the building is not classified as a broch [2]. However both the scarcement and the doorway into the wall from the Central court, as well as the suggestions that part of the gallery is an upper one, strongly suggest that An Sean Dun is a hollow-walled broch.

Dimensions. The internal diameter is given as 9.0m and the wall thicknes as 3.0m [2]. The 1989 angle-and-distance survey of the central court below scarcement level has not yet been analysed (the drawing is in the National Monuments Record).

Sources: NMRS site no. NM 45 NW 3: 2. RCAHMS 1980, 98, no. 177, fig. 100 and pl. 15, A: 3. Feachem 1963, 182: 4. Ritchie and Harman 1996, 124.

E W MacKie 2007


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