Montalto House, Dromore Road, Ballymaglave north, Ballynahinch, Co Down, BT24 8PX

Montalto House is a large three-storey mansion with a hipped roof, built in a restrained late Georgian style with mild classical detailing. The building features a prominent full-height canted bay to its front elevation and is finished in render and sandstone.

The house originally dates from the mid-18th century but assumed much of its present form in 1837, when the ground level around the original two-storey house was lowered to create the current three-floor structure. During this remodelling, the main entrance was probably shifted from the south to the east, a large wing was added to the north, and the south wing—perhaps the original front—was probably remodelled. In subsequent decades the house was further expanded at the rear with the addition of a ballroom to the south-west and a service wing. In 1953 the ballroom and much of the service wing were demolished. Following a fire in 1985, much of the north wing also had to be taken down. In the mid-1990s the building was completely renovated and a new large two-storey, sympathetically designed extension was added to the truncated north wing.

The building is set within a large demesne to the south of Ballynahinch, with wooded areas to the north, south and west, and a small lake to the east roughly in the shape of a fish.

The front façade faces roughly east (east, south-east) and is symmetrical. At its centre is a full-height projecting hipped ashlar sandstone bay which is canted to the first and second floors but square to the ground level. The main entrance is located at the centre of the east face of the ground floor of the bay. It consists of a mainly glazed door encased with fluted Doric three-quarter column jambs. Beyond these are large sidelights with margin panes and plain aprons. To the outer edges of the sidelights are plain pilasters. This whole door and sidelight ensemble is topped with a modillioned frieze with cornice and forms a shallow bay within the main porch bay. The outer corners of the porch have plain pilasters, with iron ornamental lamps attached to the wall between the pilasters and the shallow bay. To the short north and south faces of the main porch bay there are edge pilasters and a central semicircular arch-headed recess.

To the first floor of the main central bay there is a Georgian paned sash window (six-over-six) to each face with simple surround with frieze and entablature. Almost all the windows to the house have sash frames. To the second floor are much shorter sash windows (three-over-six) with plainer surrounds. To the ground floor, either side of the bay, there are tall semicircular arched recesses. Beyond each of these there is a single outer window of similar arched shape with sash frame (ten-over-six). To the first and second floors there are two windows to either side of the bay which match the windows to the corresponding levels on the bay itself. All the first and second floor windows rest on a string course. The outer portions of the front façade are in lime-washed lined render, though the string and eaves courses are in sandstone, as is the central bay.

The south façade of the south wing was probably the front of the original 18th-century house but appears to have been altered somewhat during the 1837 remodelling. To the left the roof level is lower and the façade two-storey, whilst to the right it is three-storey; however, as will be seen later, the left-hand section is actually three-storey to the rear. The left-hand portion of the façade is largely symmetrical, with a full-height canted hipped-roof bay, three windows to each floor of the bay and two to each side of each floor beyond the bay. All the windows are semicircular arched with sash frames (ten-over-six to ground level, seven-over-six to first floor). To the central ground floor face of the bay the arched opening actually contains a glazed door, though there may originally have been a window here.

To the right edge of the three-storey right-hand portion of the south façade there is a full-height bay similar to that to the front, but rendered and canted to the ground floor. There are windows to each face of the bay at each level. The ground floor windows are of the arched variety as ground floor left of the façade, whilst those to the first and second floors are as the bay to the front façade. To the ground floor left of the bay are two further arched windows. To the first floor left of the bay is a window to the left as first floor of the bay itself. To the right of this is a large tripartite window (four-over-four, six-over-six, four-over-four) with thick pilaster mullions set on brackets and a plain frieze and cornice. To the second floor are three windows as second floor of the bay. The whole of the south façade, bar string and eaves courses, is in lined render.

The north façade of the north wing is very much a handed version similar to that to the south. To the left the three-storey section has a bay to the far left and that to the right matches that on the south façade. The ground and first floors to the right of the bay match the equivalent area to the south façade also, but with an extra single sash window to each floor. To the ground floor there is an arched window to the left (as ground floor south), with two smaller flat arch windows to the right (both six-over-six). The two-storey section to the right has its canted bay to the left-hand side. To each face on each floor of the bay there is an arch-headed window, all seven-over-six. To the right of the bay there are three similar windows to each floor. The north façade is rendered as the south.

The rear elevation consists of the gable of the two-storey section of the north wing to the left, the uneven gable of the south wing to the right, and, in the centre and set much further back, the exposed rear façade of the main front wing. Set a distance in front of the rear façade of the front wing is a recently added single-storey corridor link which spans between the north and south wings. This link (along with the wings of course) creates a small courtyard in which there is a small garden area. The whole rear elevation is finished in lined render. The gable of the north wing has an arched window to first floor left (seven-over-six) and a taller arched window (ten-over-six) set at an intermediate (stairwell) level to the right. The gable of the south wing has an uneven appearance, as the wing is actually three-storey to the north side and two-storey to the south (see above). There are two flat arch windows to the left, both six-over-six and both set at intermediate (stairwell) levels.

To the ground floor of the rear façade of the main front wing there is a small four-pane window to the far left and far right. Above this is a large multi-Georgian pane semicircular arched window which lights the main stairwell. To left and right of this is a small six-pane window. To the second floor are two six-over-six windows. To the left of these, actually on a section which was once probably an internal wall of the north wing, is a tiny single pane window.

The north façade of the south wing is three-storey and completely finished in lined render. To the ground floor there are three semicircular arched windows (seven-over-six) to left and centre. To the right the façade is abutted by the linking corridor. To the first floor there are five plain windows (six-over-six) with five similar but smaller windows (still six-over-six) to the second floor. The south façade of the north wing is two-storey. To the ground floor are three windows as ground floor previous, with four windows to the first floor, also as previous. This façade is also finished in lined render.

The linking corridor is single-storey, flat-roofed and appears to be entirely timber clad. To the centre of the west face is a large mainly glazed double door. This is flanked by large tripartite windows (two-over-two, six-over-six, two-over-two). The rear (east) face appears to have a similar arrangement.

The roof is largely hipped and is entirely slated. There is a lead-sheeted parapet. There are five rendered chimney stacks with possibly sandstone corbelling and matching pots. Cast iron rainwater goods.

Stretching from the right-hand edge of the north façade is a tall rubble wall with brick dressings. To the south end of the wall there is a large gateway with recent-looking metal gates. To the north end the wall culminates in an unusual three-storey flat-roofed garden tower of pre-1858 construction, also in rubble and brick, but topped with a sandstone frieze course and cornice. The tower has glazed windows to the east and some semicircular arched recesses to the south and north. To the south a staircase and walkway, built to the rear of the high wall, leads to a first floor semicircular arched doorway. To the west the tower is abutted by a relatively small single-storey gabled return belonging to a not insubstantial two-storey gabled house. This house, once perhaps a butler's residence, is in recent-looking lined render with brick dressings and quoins. The windows are generally quite small and filled with two-over-two sash frames, and the doors are timber framed, with a large partly glazed patio door also in evidence. The front doorway appears to be that located on the south face of the small single-storey return to the east. To the west façade a large utilitarian-looking single-storey garage extension with mono-pitched roof has been attached. The gabled roof is slated and there are three brick chimney stacks, one stretching from the garage.