The cathedra of the Bishop of Clogher was removed to Monaghan town in the mid-19th century. The plan for the cathedral was proposed in 1858 by Bishop Charles MacNally. The site was purchased in 1861. Architect James Joseph McCarthy (1817–1882) designed the cathedral in a 14th-century Gothic architectural style was begun in 1862. Most limestone was quarried locally. Architect William Hague Jr. (1840–1899) from Cavan oversaw the building of the spire after 1882, which stands 81 metres high, as well as the gate lodge. Bishop James Donnelly, bishop of Clogher from 1864 to 1893, oversaw most of the building and dedicated it on 21 August 1892 to the service of God and the patronage of Macartan, the diocese's patron saint.