Roscommon Castle might not see many tourists but it is worth a look if you are near Roscommon town. The town of Roscommon is about a 30 minute drive from Carrick-on-Shannon or a 1 hour drive from Sligo. The castle and surrounding park is located just outside Roscommon town.
Roscommon castle was built in 1269 by Robert de Ufford. Today it is only a ruin but you can download a pdf file from the Roscommon County Council that contains illustrations of what the castle would have looked like in medieval times.
Roscommon Castle is not shown on Google Maps. It is located within the grounds of Loughnaneane Park. The gps coordinates are N 53° 38′ 07.9″ W 008° 11′ 35.2″