The building was originally established as Charlemont Place National School and the architect may have been Francis Johnston's pupil, William Murray.

The Society and museum expanded during the latter half of the nineteenth century and by 1888 it had 275 members paying an annual subscription of five shillings each.

He found many of the "curiosities" collected by the Philosophical Society to be of little value to a modern County Museum and advised "that the few scattered ethnographic objects should be likewise jettisoned, including the very dilapidated mummy...".

This was completed by 1937 and on 28 April of that year, James Caulfeild, 8th Viscount Charlemont in his role as Minister of Education for Northern Ireland performed the opening ceremony.

[citation needed] Although he was from a farming background, young Thomas was apprenticed to a Portadown grocery business, Davidsons.

[11][not specific enough to verify] He also commissioned a work by Belfast-based artist John Luke, who had moved to County Armagh to escape the blitz during the Second World War.

Over the years he managed to persuade a number of Russell's contemporaries, including Lily Yeats, to donate paintings and personal articles associated with the artist.

Uniforms and accoutrements from the period of the Volunteers in the 1780s were acquired, as were harvest knots and rush-light candleholders used by the rural communities of South Armagh.

By the late 1950s, the museum had expanded to capacity and Armagh County Council was persuaded to spend money on an expansion programme.

Paterson and Weatherup spent several months of 1959 packing up the collections and emptying the display cases in readiness for the major refurbishment.

[citation needed] During the closure of the museum all of the old buildings behind the neoclassical facade were demolished including the 1890s Art School.

The close relationship with the Ulster Museum brought many advantages,[citation needed] not least the ability to rely on the skills and resources of the larger institution.

[citation needed] A chance to expand the museum was realised in the early 1980s when the construction of a dedicated Library Headquarters on the outskirts of Armagh city at Woodford meant the ground floor became vacant.

It has continued as one of the four components of National Museums Northern Ireland since then and like the other sites is funded by the Department of Culture Arts and Leisure (DCAL).

In April 2015, as part of Northern Ireland's Review of Public Administration the museum was transferred to the newly formed Armagh City, Banbridge and Craigavon Borough Council.

[citation needed] The English watercolour artist Cornelius Varley toured Ireland in 1808 and his pencil drawings of Armagh city and Markethill are also in the collection.