Description
The monument comprises the remains of a small and potentially very early stone castle sited on an islet in the Loch of Strom, together with the remains of the stone causeway that connect it to the shore. Researchers suggest the castle may date to as early as the 12th century. The main castle building is a rectangular tower measuring 6.5m E-W by 5.6m transversely, with walls between 1m and 1.4m thick. Most of the walls now stand less than 1m above ground level, but at the NW corner of the tower, the W wall stands about 2.5m tall. The walls are constructed of rubble blocks built with shell-lime mortar. The foundations of other buildings have been identified further east and other traces of masonry suggest that the island was once completely enclosed by a stone wall. The causeway is about 50m long and, although partially submerged, is visible as a narrow line of boulders. The island lies off the W shore of the Loch of Stom, a tidal sea loch, close to its S end, and stands barely above sea level. The monument was first scheduled in 1953, but the documentation does not meet modern standards: the present rescheduling rectifies this.
The area to be scheduled is irregular on plan, to include the remains described above and an area around them within which evidence relating to the monument's construction, use and abandonment may survive, as shown in red on the accompanying map.
Statement of National Importance
Cultural Significance
The monument's cultural significance can be expressed as follows:
Intrinsic characteristics
Although the upstanding walls have been robbed and facing stones are missing from the base of the W wall, the ruin seems to have been stable for several decades. There is no evidence of disturbance to the castle site other than the removal of stones from the upstanding structure, which suggests that buried archaeological remains will survive in good condition. There may also be waterlogged deposits given the castle's island location, which could preserve rare organic remains. There is potential to examine in detail the construction and form of the castle, its development sequence and dating, and its relationship with the wider landscape. The likely presence of remains from different periods gives the possibility of exploring issues such as the duration of occupation, the extent to which occupation of the site was continuous and the nature of abandonment processes.
Contextual characteristics
Researchers have suggested that this castle resembles Cobbie Row's Castle, a structure on the island of Wyre in Orkney. Both castles have a small rectangular tower and documentary evidence suggests that the Orkney example was built in 1145. A former church lies on the loch shore 150m SW of Castle Holm, and there is potential to study the relationship between the two sites. A ruinous late 12th-century chapel lies adjacent to Cobbie Row's Castle, suggesting that strongholds of this date were often provided with a small private chapel. The structure on Castle Holm has considerable significance because only two other castles are known in the Shetland Islands, at Scalloway and Muness, and they date to a much later period, the turn of the 16th century. Moreover, Castle Holm has wider significance beyond the Northern Isles because, if contemporary with Cobbie Row's Castle, it would be one of the oldest two medieval castles of stone and lime to survive in Scotland. As well as comparing the structure with other early castles across Scotland, there is also potential for researchers to examine the castle in the context of the medieval settlement pattern in the vicinity.
Associative characteristics
There is no known documentary evidence to clarify when this castle was built. The site is marked on the Ordnance Survey 1st edition map and is labelled 'Castle (Ruins of)'.
National Importance
This monument is of national importance because it has an inherent potential to make a significant addition to our understanding of the past, in particular, the earliest medieval castles built in Scotland. There is high potential for well-preserved archaeology to survive that can make a significant contribution to our knowledge of the development of early castles. Its significance is enhanced by the capacity to compare it with Cobbie Row's Castle on Orkney and with other potentially contemporary sites in the vicinity. The loss of the monument would significantly diminish our future ability to appreciate and understand the early stone and lime castles of Scotland.