The Great Light is one of the largest optics of its kind ever built in the world, and is around 130 years old. Weighing 10 tonnes and measuring 7 metres tall, the optic is a unique maritime heritage object with significance to Belfast's economic, maritime and industrial past. It is totally irreplaceable and is an exceptionally rare maritime artefact. It produced one of the strongest lighthouse beams ever to shine.
The Commissioners of Irish Lights, often shortened to Irish Lights or CIL, is the body that serves as the general lighthouse authority for Northern Ireland and the Republic of Ireland and their adjacent seas and islands. As the lighthouse authority for the island of Ireland it oversees the coastal lights and navigation marks provided by the local lighthouse authorities, the county councils and port authorities.
It is funded by light dues paid by ships calling at ports in the Republic of Ireland, pooled with dues raised similarly in the United Kingdom. This recognises that a large volume of shipping, typically transatlantic, relies on the lights provided by Irish Lights.
Signal fires to guide shipping have long existed. Hook Head has the oldest nearly continuous light in Ireland, originally a signal fire or beacon tended by the monk Dubhán in the fifth century. Monks continued to maintain the light until the Cromwellian conquest of Ireland in 1641.
King Charles II re-established the lighthouse in 1667. He granted a patent for the erection of six lighthouses to Robert Reading, some replacing older lighthouses, at Hook Head, Baily Lighthouse at Howth Head, Howth sand-bar, Old Head of Kinsale, Barry Oge's castle (now Charlesfort, near Kinsale), and the Isle of Magee.
In 1704 Queen Anne transferred the lighthouses around the Irish coast to the Revenue Commissioners.
The Commissioners of Irish Lights were established under an Act of the Parliament of Ireland passed in 1786 and entitled An Act for Promoting the Trade of Dublin, by rendering its Port and Harbour more commodious (26 Geo. III, c. xix). Lighthouses were not included until an 1810 Act of the Parliament of the United Kingdom of Great Britain and Ireland. These Acts, modified by the Irish Lights Commissioners (Adaptation) Order, 1935, remain the legislative basis for the CIL.
Irish Lights has moved its headquarters from Dublin to a purpose-built new building in Harbour Road, Dún Laoghaire.