All Saints Church of Ireland, Eglantine Road, Hillsborough, County Antrim, BT27 5RQ

All Saints Church of Ireland is a free-standing memorial chapel built to the designs of Sir Thomas Drew, with construction beginning in 1874 following the laying of the foundation stone on 27th June of that year. The church was consecrated on 15th July 1875 and first appears on the Ordnance Survey map of c.1902. It stands on an east–west axis on the east side of Eglantine Road, to the south of the M1, in the townland of Carnbane, slightly north of Eglantine House and a few miles north of Hillsborough. It is considered by architectural historian C. E. B. Brett to be the finest church ever designed by Thomas Drew.

The church was commissioned by Margaret Mulholland, then occupant of Eglantine House, as a memorial to her late father, St. Clair Kelburn Mulholland (died 1872), and her brother of the same name (died 1861). Before construction began, the Irish Builder reported that the church would be "situated within [her] demesne and will be a prominent feature in a pleasing rural landscape, viewed from the windows of the Mansion," and that the architect had "endeavoured to make it simple rather than imposing, and quite picturesque." The church was built to accommodate a congregation of around 250 parishioners. It was constructed by Messrs Lowry and Son, and although the Irish Builder estimated the cost at £2,000, the final recorded cost came to £3,442 5s. 10d. The Dictionary of Irish Architects identifies Sir Thomas Drew as an old and attached friend of the two men commemorated by the building.

Sir Thomas Drew (1838–1910) had worked for Charles Lanyon and designed many churches throughout Ulster before being appointed diocesan architect of Down, Connor and Dromore in 1865. He was knighted in 1900 as part of the Queen's birthday honours. Brett describes the church as built in a distinctly English style with walls of blackstone and small red roof tiles.

In 1880, the Annual Revisions record that Margaret Mulholland had allocated over an acre of land for the construction of the church, and that the new church and land were first formally valued at £38. A gate lodge originally intended for the Mulholland Estate was also gifted and used as the sexton's house, valued at £4. The church's valuation remained at £38 until the end of the Annual Revisions in 1929.

The Mulholland family maintained a strong influence over the church — providing the sexton's house, a school house at Newport, and a rectory (Wellington Lodge) — until 1917, when the last surviving family member died. Brett writes that "they were generous indeed to this country parish, and uncommonly well served by their architect." Originally part of Christ Church and Broomhedge parishes, Eglantine was at some stage constituted as a small parish in its own right. In 1924, a new pipe organ was installed. The church was listed in 1977, and in 1995 a new parish hall was added in the churchyard to mark the 120th anniversary of the church. The roofing was re-tiled around 2008.

A notable local detail is that the old Lagan Canal once cut the church off from parishioners to the north of the Eglantine Demesne. To allow people from the Maze and other areas to attend services, All Saints employed a boatman for £1 a year to ferry people across the canal.

The building is rectangular on plan and constructed in a formidable Early English style. Walling to the north and west elevations is of rock-faced random rubblestone basalt with a splayed plinth course, sandstone ashlar quoins, and diagonal buttresses to the west gable. Pointed-headed window openings throughout have red sandstone relieving arches, flush sandstone surrounds, and diagonally-leaded glazing. The roofs are pitched with terracotta tiles and ridgecomb tiles, set slightly below sandstone copings to all gables. Gables are finished with moulded kneeler stones and surmounted by stone Celtic crosses. The apsidal chancel has its own terracotta-tiled roof surmounted by a lead cone and cross. Iron dog-tooth box guttering is supported on exposed shaped rafter feet, with cast-iron downpipes. A decorative stone chimneystack rises from the south nave wall behind the vestry.

At the angle between the east gable and the chancel, an angled buttress rises to form a sandstone ashlar gablet belfry with bowtel mouldings, a gothic bell arch, three iron bells, and an iron crest with weather cock.

The south nave elevation features a catslide roof at the same pitch as the nave, covering the south aisle. To the east of this elevation is a single-storey vestry block with pointed-headed door and window openings formed in flush chamfered sandstone surrounds, a diagonally-sheeted timber door, and leaded windows. Also on this elevation is a decorative open timber entrance porch with an exposed scissor truss timber roof, leaded glazing to the cheeks, and low rubblestone walls with sandstone coping. Within the porch, the floor is laid in black and red clay tiles. The pointed-headed sandstone doorcase comprises a vertically-sheeted timber door with decorative iron door furniture, flanked by a pair of engaged squat columns and a compound arch with hood moulding.

The west gable has a trefoil-headed double-height window opening with rough red sandstone voussoirs and flush sandstone ashlar plate tracery, comprising a pair of trefoil-headed lancets with a sexfoil above. All openings have bowtel reveals, splayed sills, and leaded glazing. The north nave elevation is four windows wide, with pointed-headed openings with red sandstone voussoirs alternating between trefoil-headed lancets and plate tracery matching the west window design. The east elevation is abutted by the apsidal chancel, which has six trefoil-headed lancet openings on a continuous sandstone sill band.

The church was designed to have a generally rich but unpretentious interior. The Irish Builder described the interior treatment as "ornately designed" to provide a "generally rich but unpretentious treatment." The interior retains all its original features.

The sexton's house is contemporary with the church and is likely also the work of Sir Thomas Drew. A panel on its front wall reads "Sexton's House 1875." Brett describes it as an "uncommonly pretty small L-shaped two-storey house … very much the self-conscious creation of an architect, in a mildly humorous semi-ecclesiastical vein, and exactly right in its rural setting."

The church is set within its own landscaped grounds, accessed from Eglantine Road via the car park of the modern church hall (built c.1995) along a long tarmac drive with rubble gate piers at the end of the avenue. A graveyard lies to the east, with grave markers dating from 1920. The graveyard contains, in addition to Mulholland family members and local parishioners, the remains of 21 Commonwealth Air Force men who served at the RAF aerodrome at Long Kesh and died during the Second World War. The rural setting contributes significantly to the character of the building.