St Louis Grammar School, 151 Newry Road, Kilkeel, Newry, Co Down, BT34 3ET

St Louis Grammar School is a two-storey multi-bayed range with tower constructed in two phases during the inter-war years of the 20th century, located on Newry Road in Kilkeel. The building has a pitched natural slate roof with projecting eaves courses that support cast-iron ogee gutters.

The first phase, built at the western end, is constructed of regularly coursed concrete blocks cast to simulate rock-faced stonework with strap pointing throughout. Concrete block quoins and projecting chamfered basecourse complete the base treatment. The most distinctive feature is the three-stage rectangular tower at the east end of this phase, now positioned at the middle of the entire block. The tower's top stage projects above the eaves, and its main doors—a pair of modern six-panelled doors with fixed side panels and a plain rectangular overlight—are positioned on its right (west) cheek. All openings throughout feature chamfered concrete jambs and heads. Each upper floor of the tower contains a pair of 6/6 sliding sash windows, though those to the first floor have been replaced in plastic. The tower's north elevation has an infilled pair of transom windows at ground floor, a pair of 6/6 sashes at first floor, and a pair of modern casements at second floor. Its left cheek displays a 6/6 sash to ground floor, a modern 6/6 sash to first floor, and a pair of 6/6 sashes to second floor. The tower's cornice is machiolated and the roof is steeply pitched and hipped, creating a short ridge crested with lead finials.

On the main block to the right of the tower are six matching openings. Except for the most westerly bay, which has a single 4/4 sliding sash, each bay at ground floor contains a pair of large 4/4 sliding sashes set within a single opening. Above these, a pair of similar but smaller windows are separated by a masonry pier. A narrow 2/2 sash occupies the extreme left. A single-storey porch abuts the western opening, featuring a pitched natural slate roof, matching façade walls, and a pair of 4/4 sliding sashes on its north gable, with a door to its left cheek and a blank right cheek.

The west gable of the main block has a raised and coped parapet with a finial cross. A full-height window with a solid concrete panel divides the ground and first floors, displaying the arms of the diocese and the nuns of St Louis, with plain chamfered concrete head, cill and jambs.

The rear elevation mirrors the front but extends only eight bays wide. In the east bay stands a single-storey porch with a crenellated parapet, featuring a Gothic door to its south elevation and a 1/1 casement to its left cheek. At the far right, where the second building phase adjoins, a single-storey timber link corridor with shallow flat roof connects to the former convent house to the south. The rear elevation displays pairs of 4/4 sliding sashes at ground floor and paired smaller 4/4 sliding sashes at first floor, these latter not sharing the same opening.

The second phase extends to the left of the entrance tower across ten bays, terminated by an advanced three-bay hipped section set at right angles at its east end. This section shares the same concrete block construction and dressings as the original, but without a raised basecourse. Its pitched natural slate roof has informally placed ventilators along the ridge. A door is positioned in the middle bay of the advanced east section. Large steel casement windows punctuate each bay on both floors, with first-floor windows diminished in height. The rear elevation is similarly arranged.

A post-World War II three-storey extension abuts the east end of the advanced end bay, matching the height of the adjoining block. It features a flat parapeted roof, grey brick walls, and vertical curtain walling with painted fixed apron panels.

Tarmac playgrounds front the building.