Ballincollig Castle is a ruined Norman tower house on the south side of town, built in the 15th century by the Barrett family, one of the Norman families who settled Cork after the invasion. The castle is a squat, four-storey tower of the kind typical of Munster's Anglo-Norman occupation, set in a small field south of the main road. It is roofless and the interior is not accessible, but the exterior walls stand to their full height.
The castle is easy to combine with a visit to the Gunpowder Mills park, being only 1.5km to the south. It has no visitor facilities and no entry charge. The surrounding area has good views south toward the Cork hills and gives a sense of the defensible position the Barretts chose — the castle overlooks the Lee valley and the approaches from the south.