Roscommon Castle is one of those places that rewards visitors who venture beyond the well-worn tourist trail. Standing at the northern edge of Roscommon town, the castle's substantial ruins — four large towers connected by high curtain walls enclosing a large inner ward — give a real sense of the scale and ambition of Norman fortification in medieval Ireland.

The castle was built in 1269 by Robert de Ufford, the Lord Justice of Ireland, as part of the Norman effort to control Connacht. It was almost immediately captured by the Irish, then retaken, then captured again — a pattern that would define its history for the next four centuries. The O'Connors, the dominant Gaelic dynasty of Connacht, held the castle for significant periods, and it changed hands repeatedly between Norman and Irish forces throughout the medieval period.

The castle was substantially rebuilt in the late 15th century, and the structure you see today largely dates from this period. The four large D-shaped towers at each corner are particularly impressive — their scale gives a sense of how formidable the castle must have appeared to anyone approaching across the flat Roscommon plain. The castle was finally slighted (deliberately damaged to prevent military use) during the Cromwellian wars of the 1650s, and has been a ruin ever since.

Entry to Roscommon Castle is free and the site is open throughout the year. The castle sits in a small park on the edge of town, making it easy to combine with a visit to Roscommon town itself. The town has a good selection of cafés and restaurants, and the surrounding County Roscommon countryside — part of Ireland's Hidden Heartlands — is well worth exploring.