The architect was Joseph Welland and Son.

A War Memorial Zion, inside the Zion Church, commemorates the members of the parish who were killed or missing in the Great War (World War I).

Joseph Welland (6 May 1798 – 6 March 1860) was born in Middleton, County Cork and became an Irish Architect for the Board of First Fruits and later the Ecclesiastical Commissioners. He was as a student to John Bowden and became his assistant and is noted to have designed many churches and schools around Ireland.

While working with John Bowden with the Board of First Fruits, he shared some of Bowden's works. These include St. Philip and St. James Church, Booterstown and St. Stephen's Church, Mount Street (The Pepper Canister), both of which Joseph Welland had to complete himself after Bowden's death in 1821.

Joseph Welland died on 6 March 1860 and was buried in St George's churchyard, Dublin.

His younger son William Joseph Welland (1832-1895) also designed churches, and worked for the Ecclesiastical Commissioners.

The High School is a 12–18 mixed, Church of Ireland, Independent secondary school in Rathgar, Dublin, Ireland. It was established in 1870 at Harcourt Street before moving to Rathgar in 1971 and amalgamated with The Diocesan School for Girls in 1974, becoming co-educational.

In 2009, it was ranked as the best-performing school in Ireland in terms of progression to third-level education and is part of the Erasmus Smith Trust.