This large commodious edifice ranks as one of the oldest buildings in Roscommon town and also the County as a whole. It probably resulted from the new military strategy formulated after the Jacobite War of the 1690’s and remains as one of the best examples of Georgian Architecture in the area.
Parliamentary Papers dated 1813-48 stored at the Department of the Archives of the British Army Museum in London, contains lists of Irish Barracks with highly detailed figures of the various features of each building. Roscommon in no exception, dimensions of rooms, number of windows, number of people occupying it ventilation etc. are given as well as date of erection 1702. In 1813 a list shows how 163 men were accommodated at a cost of £160 yearly by one named as A Thompson. Obviously this accommodation must have been extra housing provided in the town as a number of the proprietors were listed as well. A map from the same source dated 1832 shows the barrack, parade ground, hospital, turfyard and well. In 1704 one troop of horse (cavalry) was stationed here which consisted of 36 troopers, a Captain, a Lieutenant, a Cornet, a Quartermaster, 2 Corporals and a Trumpeter.
As can be seen as the century wore on the Barrack itself became too small to accommodate the increasing number of men especially during the 1798 Rebellion and the Napoleonic Wars. In 1813, 163 men were listed as members of the garrison housed in the town.The parade ground and Barrack Lane were greatly altered when the Midland & Great Western Railway was expanded to Roscommon from Athlone in 1860. Cost cutting exercises towards the end of the Century favoured Athlone at the expense of Roscommon. It appears to have at least functioned until after 1882. A newspaper report from that time shows a Lieutenant Watkins of the 64th Regiment stationed in Roscommon town giving a character reference for two soldiers falling foul of the law.
Estate Agent William Black bought it for £600 in 1907 and it is believed to have been vacant for some time before. At the main gate and a side gate musket loops guard the approaches to the building. It is now owned by the County Council.