The former St Mary's Convent is sited on a hill overlooking the Endeavour River. It is constructed in red brick in a
Victorian Gothic style. It has an L-shaped floor plan with a bay projecting to the west on its northern end. Brick
cornices surround the building below the ground-floor- and first-floor-window levels and at first-floor level. The roof has a steep pitch and is now clad in corrugated iron replacing the original ribbed pan. The roof finishes as a
gable over the western bay and as a truncated
hipped form at the southern end. The original decorative ridge cast-iron work and roof vents have been removed from the truncated section of roof. Later
dormer windows have been installed with four along the east elevation, one on north side and two on the west elevation. There are verandahs on the east and west elevation. The west or front verandah is supported on paired cast-iron
Corinthian columns which divide it into five bays. Each bay is finished with arching decorative cast-iron
brackets. The paired columns at first-floor level rise in
Doric detailing to support the verandah roof. The rear or eastern verandah is infilled but retains its original detailing of single columns cast-iron first-floor
balustrade and deep vertical timbered
valance at ground-floor level. The former single-storeyed hipped roof brick kitchen building remains to the rear on the north side; additions have been made adjacent to this to service the museum. On the western bay there are three centrally positioned long, narrow windows at ground-floor and first-floor levels, and above these a round vent with
hood mould. On the north elevation there are sets of four double-hung timber windows symmetrically positioned at the ground-floor and first-floor levels; these have window hoods with scalloped
fascias. The central timber doorway with side lights is accessed via a set of stone
stairs from the western verandah. This doorway is flanked on each side by double-hung windows with shallow arched heads and hood moulds over. The apex of the western gable roof has cast-iron panels fixed between a collar tie supported by decorative timber brackets and a
king post running up to the roof and supporting a cross. The central hall contains a fine timber staircase. Rooms of various dimension run off central corridors at ground and first-floor levels. The rooms in the northern end of the building provide large museum display space. Walls are plaster over brick and ceilings lath and plaster with moulded decorative cornices. == Heritage listing ==