11 Harbour Road, Carnlough, Ballymena, Co Antrim, BT44 0EU

This mid-19th century building stands at the south end of Carnlough Harbour in County Antrim. Built around 1855 as offices for the limestone works, it was part of improvements undertaken by the Marchioness of Londonderry in the early to mid-1850s. The building is situated beside the railway bridge that transported limestone and other mineral ores from inland quarries to the harbour; both the bridge and harbour were completed in 1854. The building appears on the Ordnance Survey map of 1855 and was long known as Harbour House.

The structure is a two-storey building of asymmetrical layout, featuring a stepped gable to one side of a crenellated entrance tower with its main entrance facing north. Roofs are covered in Bangor blue slates in regular courses. Walls are smooth rendered with quoins at the extremities of the end bays.

Windows are predominantly rectangular timber sliding sash of 2 over 2 lights with horns, set in plain reveals. The first floor of the entrance tower contains a Gothic arched window—a timber fixed light with a top-hung lower light—set within a raised Gothic arched surround with chamfered reveals. The ground floor of the tower has a rectangular timber glazed and panelled door with a plain rectangular fanlight above, set in plain reveals, flanked by later fluted timber panels with a wooden panel over the head.

Modern shop fronts have been inserted in blocks flanking the tower, and a large modern shop sign is fixed to the upper part of the tower front. The side elevations are smooth rendered; the west wall contains similar sashed windows, while the east wall has rectangular timber fixed lights with top-hung vents. The rear elevation is plain in character and includes blind rectangular window openings.

The building has undergone significant refurbishment and extension and has lost a number of original features, so it no longer presents an original appearance externally or internally. It was renovated by architect Paddy Byrne as part of the Carnlough Harbour refurbishment scheme of 1993.

The building stands within the village's built-up area, set back slightly from the main street behind a rendered boundary wall. Its formerly enclosed front plot is now open, forming part of the public space within the harbour area. Immediately behind it is the embankment of the former railway line, now a pedestrian way, accessed by a new flight of steps at the front of the building. The site is of industrial archaeological interest and lies within the Carnlough Conservation Area.