Tom an Tigh Mhoir, meaning “mound of the big house”, is a motte standing on a flat promontory created by the confluence of the River Garry and Errochty Water.
Little is known about Tom an Tigh Mhoir, however the area around Struan has a strong association with Clan Donnachaidh – specifically the Robertsons of Struan – and it may be that they were responsible for building it.
The nearby Struan kirk is built on the site of an early medieval church dedicated to St Fillan, possibly dating back to the 9th century. The church and the motte are around 140m apart and both stand on a flat area of land bounded to the north by the River Garry and to the south by the Errochty Water, giving the motte a good defensive position. The land drops away steeply on the north side of the motte to the river below, further enhancing its defendability.
The south and west sides are defended by a substantial ditch which runs from a rounded terminal at the middle of the south side up to the north-west corner where it meets the drop down to the river. There is no visible evidence of a ditch on the east side, but it’s conceivable that it may have been filled in during agricultural improvements to the land.
The motte rises to a height of around 5.2m at the north-east corner and around 4.6m on the west side.
The top of the motte is flat and of irregular quadrilateral shape, measuring approximately 19m across.
The footings of a rectilinear building or enclosure can be seen on the summit, but these have been interpreted as relatively modern structures post-dating any defensive building.
A wall running down the south slope may date to a similar period and is unlikely to be contemporary with the motte. A legend states that a local laird began building a house on the summit but abandoned construction when a neighbour built a higher castle on the other side of the River Garry.
Interestingly maps of the late 18th and early 19th centuries show a substantial house belonging to the Robertsons sited to the west of Struan kirk, although this was presumably not on the motte itself but to the west of it (possibly being related to the footings of building noted by the RCAHMS at NN 8057 6543).
It has been suggested that this may not be a mound at all but a moot hill or meeting point. However it does compare in shape and size with several mottes across Scotland, so it seems likely that that is what it is.