Roscommon Castle, a 13th-century Norman structure, was built in 1269 by Robert de Ufford, Justiciar of Ireland, on lands which were taken from an Augustinian priory.

The castle was laid siege by the Connacht King Aodh O'Connor in 1272. Eight years on, it was once more in the possession of the English garrison and fully restored. By the year 1340, the O'Connors had regained possession and held it until 1569, when it then fell to Sir Henry Sidney, the Lord Deputy.

In 1641, it was obtained by the Parliamentarian faction and then confederate Catholics, under Preston, captured it in 1645. From then, it remained in Irish hands until 1652, when it was partially blown up by Cromwellian 'Ironsides', who then had all the fortifications dismantled. The castle was burned down in 1690 and ultimately fell into decay.

Today, the Castle's past can be explored while enjoying adjacent Loughnaneane Park and Playground, a 14-acre recreational area.

The natural features of the park include a turlough and a wildlife conservation area, which is a habitat of unique flora and fauna. A deck is provided for visitors to view the wildlife and vistas beyond. There is also a swallow hole onsite. The Park includes a crannog known locally as the Hill O' Bones, a wildflower meadow, bird walk, lake feature, mounds, children's playground, and car park.