St Mary's Star of the Sea, 4 The Crescent, Portstewart, Co. Londonderry, BT55 7AB

St Mary's Star of the Sea is a large, free-standing Roman Catholic church built between 1913 and 1916 to designs by architect William J. Moore. Constructed in the Lombardic Romanesque style, it stands on the east side of The Crescent in Portstewart town centre, overlooking the harbour. It is one of only three known ecclesiastical commissions by Moore, the other two also in coastal locations at Glenariff and Cushendall. The church replaced an earlier Catholic chapel erected in 1895 at Heathmount — a corrugated iron building known locally as the 'Tin Chapel' — which the congregation had outgrown. Tenders for the new church were invited in 1913, and the total cost was £6,000, of which £3,000 was bequeathed by John Glenn of Coleraine. The contractors were Thornbury Brothers of Belfast. A photograph survives showing the church under construction in 1915, together with some of the tradesmen and labourers on site; two of those men were tragically drowned while bathing off nearby rocks. The church was completed in 1916 and first entered valuation records that same year, assessed as a Roman Catholic chapel and yard valued at £140.

The building is constructed of uncoursed rock-faced blackstone — local black basalt — with ashlar sandstone dressings throughout. The roof is natural slate with cross finials to the gables, and the tower carries a leaded copper roof also surmounted by a cross finial. Cast-iron ogee rainwater goods are fixed to cavetto-moulded sandstone eaves. Windows throughout are round-headed leaded-and-stained glass casements set in block sandstone surrounds with chamfered sills and hood moulds with stops.

The plan is rectangular with a central breakfront, a four-stage square tower to the northwest, a sanctuary and baptistery to the east, and a side-chapel to the south.

The principal elevation faces ecclesiastical west. It is squared with a parapet over a plain frieze and dominated by a soaring gabled breakfront. This breakfront features a double-height semi-circular arched recess framed by semi-engaged columns, embracing a large rose window and the principal entrance, all carried out in ashlar sandstone. A central carved frieze with Celtic ornamentation runs between the stages; there is carved detail to the spandrel base of the window and to the tympanum, and a staged blind arcade to the apex. The breakfront is flanked on each side by a paired window at ground floor level and an arcaded first-floor opening of five arches, alternately glazed and blind. A sandstone string course runs along the northwest elevation, and a sandstone plat-band is set at sill level along the nave.

The tower has an open belfry with round-headed paired openings flanked by pilasters. The second and third stages are each divided into two panels articulated by sandstone ashlar lesenes, with loop openings at each face. At ground floor, there are round-headed windows to the northeast and southeast faces. The northwest face has a deeply recessed original round-headed twelve-panel timber door with cast-iron strap hinges, set in a chamfered sandstone surround with a hood mould and stops, accessed via two stone steps.

The north elevation has five evenly spaced windows divided by a gabled buttress, with a projecting confessional at the centre, featuring a lean-to roof and three diminutive windows. The east elevation has the sanctuary abutting the gabled bay, which contains three round-headed windows with hood moulds. The east rear elevation has a canted bay with a slate roof and four round-headed windows.

The south elevation has three evenly spaced windows divided by buttresses, abutted to the right by the gabled side-chapel. The west elevation of this side-chapel projects at ground floor level, with a blind oculus above a large rose window. The chapel entrance is a central round-headed sandstone ashlar doorcase flanked by semi-engaged columns and surmounted by a gabled parapet with a moulded cornice. The original twelve-panel timber door with cast-iron strap hinges is accessed via a modern ramp with a metal handrail, and the doorcase is flanked by two oculi on either side. The south elevation is abutted by a flat-roofed sacristy which connects to the adjoining manse, with a modern entrance porch to the rear. The design of the side-chapel's entrance received particular attention during construction owing to the exposed position of the site; the chapel was intended for use during the winter months and could function independently of the main church, with its own separate entrance, confessional, and sanctuary.

The interior woodwork is of pitch pine, and the ceiling is of fibrous plaster divided into panels with wood mouldings. Two holy water stoups in the church were recovered from the grounds of an old monastery in Coleraine and from Killowen churchyard. The church was designed to accommodate 600 people and was planned with the widely varying congregations of summer and winter in mind.

The site chosen for the church was a large plot on which a dwelling already stood; a portion of that building was altered to form the sacristy, with a communicating corridor connecting it to the church. A parochial house on the site was rebuilt in 1918. In the early 1990s a gate pier was repositioned to accommodate vehicular access, and stone cleaning and pointing were carried out at the same time. In 2000 a new rear porch and disabled toilets were added, and an office block was replaced.

The church stands on a rectangular plot with lawned and shrubbed ground to the front and a tarmacadamed parking area accessed via square blackstone and sandstone piers with gablet caps. The site is bounded by a rock-faced blackstone wall with sandstone saddleback coping topped by iron railings. The church is slightly elevated, with a grassy bank to the front containing a central set of six sandstone steps enclosed by a parapet wall and iron handrails. To the northeast lies Portstewart Town Hall, and to the southwest stands the Dominican Convent. Also on the site is a two-storey parochial house, now much altered. The architectural detailing is largely intact and of particular quality and character, with some fine examples of carved stonework, making St Mary's Star of the Sea a significant presence on the Portstewart seafront and a building of considerable social importance to the local community.