Not far from Jonesboro lie the ruins of Moyry Castle built in the 17th Century to guard the gap of the north. It is a familiar landmark from the Belfast/Dublin railway. The castle was built by Mountjoy in 1601 to secure the vital 'gap of the north'. It was built on a natural rocky hillock by Lord Mountjoy to secure the ancient route from Ulster. The castle is a three storey tower with rounded corners and gun loops. Overlooking the pass and close by is the railway line to Dublin, built in 1852, also, using the ancient natural route from Ulster.