The present structure completed post- c.1670 '' was designed on an "L" plan, with a substantial 'scale and platt' stair leading to the first floor in the NW part of the "L". From
MacGibbon and Ross, the main building rose to five stories and the tower to six stories in height. The main building measured 55 by 32 feet (17 × 10 metres). The hall, on the first floor, measured 44 by 20 feet (13 × 6 metres). The main entrance was in the north wall of the NW wing of the castle, opposite the staircase. Accommodation would have been in the floors above the great hall. The un-vaulted basement most likely contained the kitchens. In the wider picture of Scottish architecture, by this date Invergarry was a quite old fashioned design. As well, buildings such as Invergarry were not true fortified buildings, more 'country house' than castle. In its now ruinous state, it is difficult to appreciate the former appearance of the castle. However, an accurate representation of how the castle looked in the early 18th century, shortly after completion, is available. This is a drawing prepared in 1714 by the
Board of Ordnance (see illustration left and note below). These 'military' drawings were prepared with considerable care and accuracy, so it reasonable to assume that this is a true representation of the castle as it was at that date. This drawing was used by
Charles McKean to prepare a conjectural reconstruction of the castle. While plainer and simpler, the castle very much follows the form of castles such as Crathes and Craigievar, with their tall narrow structure and wall top elaboration. While Invergarry had some six '
bartizans', it had no defensive parapets. Indeed, despite the thickness of the walls, a structure such as Invergarry would have stood very little military bombardment. The "L" wing with its open staircase was contained within a chamber approx 16 by 23 feet (5 × 7 metres), offering little defence. At ground floor level, the castle did have some defensive elements including shot-holes and barred windows, also no doubt a stout door with an iron '
yett'. The thickness of some walls may be judged as being from the incorporation of elements of the former castle and simply the requirement for strength for a five storey building. The interior of the castle, especially the hall, would have been much richer than might be expected, with possibly painted ceilings, white painted walls with wall hangings such as tapestries, a large chimney piece and furniture. Outside, the castle had a 'close' or courtyard or service yard. This would have contained various outbuildings, such as stables, workshops, a bakehouse, a brewhouse and other essential services. There would also most likely have been a
barmkin or perimeter wall around the close. All traces of these buildings have gone. == Later history ==