Ardglass (Ard glas in Irish, meaning "green high place") is a town in County Down, Northern Ireland and still a relatively important fishing harbour.

It was an important town and port in the Middle Ages, but no harbour works seem to have been constructed until after 1812. Then William Ogilvie, who had acquired the Ardglass estate, had a harbour built. Further extensions to the pier and a lighthouse were made, but in 1838 a great storm undermined the lighthouse which fell into the sea along with the end of the pier. Work on the piers was completed by 1885 and they remain in use to this day.

Ardglass contains more medieval tower-houses than any other town in Ireland, a total of four, reflecting its importance as Ulster's busiest port in the fifteenth century. It also has probably the most extensive network of merchant's warehouses from the period surviving in Ireland. These were important in the substantial grain export trade of the fourteenth and fifteenth centuries. Fortifications survive in the town from the fifteenth century, including Jordan's Castle , the most imposing of a ring of towers built around the harbour to secure the then important Anglo-Norman trading port, King's Castle and Cowd Castle . Nearby are the ruins of fifteenth century Ardtole Church.

See also

• List of towns in Northern Ireland