This article is about the Class III road numbered C4 maintained by DfI Roads. For other roads numbered C4, see C4.
The C4 forms an H-shape that is located mostly within north Lisburn. It starts on the A30 in Lisburn and follows Duncan's Road, Kirkwoods Road and Belsize Road (including spurs along Stockdam Road and the rest of Belsize Road) to cross the A513 which marks the northern edge of the city. From here the road continues for a short distance northwards before terminating at a T junction with the C5 in the village of Milltown.