St Joseph's RC Church, Downpatrick Street, Crossgar, Co Down BT30 9EA

St Joseph's Roman Catholic Church stands on Downpatrick Street at the centre of Crossgar, County Down. This Gothic Revival church was designed by architect Mortimer H. Thompson of Belfast and built between 1867 and 1870. It occupies the site of an earlier chapel erected around 1798–1800, which measured approximately 53 feet by 24 feet and contained only 38 seats. The original building was among the first structures constructed when Crossgar was merely a small hamlet clustered around Everogue's Bridge over the River Glasswater.

The church is built of random rubble grey wacke with pale sandstone dressings. Its most prominent external feature is a square tower to the east side, topped with an octagonal spire surmounted by a metal cross. The three-storey tower has double stepped buttresses, with its upper section contained between two string courses. The lower string course splays slightly outward. Fine pilasters articulate the corners of the square section, while each face at this level displays a centred decorative pointed arch feature. The north-east face bears a stone inscription dated 1870, while the other three faces each carry matching stylised Celtic crosses. Below the stepped string, a small pointed arch window appears on each face. Two matching double entrance doors occupy the ground floor, each with a leaded light fanlight set within a cusped pointed arch opening, framed with fine pilasters and moulded archivolt. The door to the south-west front appears disused, while the south-east door serves as the main entrance.

The octagonal spire sits above the square tower, connected by an octagonal section that splays or broaches onto the square section. This junction is expressed with a small gable on each of the eight faces, each gable bearing a small roundel. These gables rest on a corbelled, machicolation-like course. Alternate faces of the octagonal section contain single pointed arched openings with drip moulding, framed by fine pilasters and fitted with timber ventilation slats. The spire itself has three horizontal bands decorated with geometric patterning.

The south-west gable merges with the tower and is framed by stepped buttresses. Its upper part contains a small cusped roundel within a semicircular headed opening, framed by fine pilasters. The lower section has two equally spaced pointed arch openings, each containing paired lancet windows with roundels above, all with cusps and fine pilaster and moulded archivolt framing.

The north-west façade features reducing buttresses dividing the face into six equal bays. All bays except the second from the right contain tall lancet windows with dressings matching those elsewhere. The second bay accommodates a gabled projection housing a small altar, with paired semicircular headed windows similarly dressed. Below the window cill to the fourth bay is a small lean-to projection infilling between the buttresses.

The rear north-east gable comprises the chancel area with a pitched roof set slightly lower than the main roof. It displays a triple lancet window arrangement within dressing featuring pilasters, archivolt and cusps. The gable is framed with buttresses. To the left of this gable is a two-storey section containing committee rooms and similar facilities with a flat roof and three pointed arch windows to each floor. A single-storey gabled vestry stands to the right of the gable, with a timber door featuring shouldered dressing and a paired window arrangement with matching shouldered opening beside it. To the far right is a single-storey flat-roofed addition. The south-west and north-west faces of these rear sections are blank, while the north-east face has plain window openings to the left and right of a centred door opening, all with plain cement dressings.

The south-east façade is divided into six bays, the first of which is obscured by the projecting tower. The remaining bays contain lancet windows as previously described. The fourth bay has a small lean-to projection matching that on the north-west elevation. To the far right is the flat-roofed extension containing three pointed arch windows to the first floor and two pointed arch headed windows to the left of the ground floor, with a pointed arch headed door to the right. The south-east face of this addition is blank.

The main roof is covered with blue slate, with cast iron rainwater goods supported on a projecting eaves course. The walls rise from a shallow projecting base course. The two flat-roofed extensions were added in recent times.

The property includes decorative wrought iron gates mounted within granite gate posts, each topped with a steeply pitched roof-like capstone.