Located on the Titanic Walkway, the Great Light is one of the largest lighthouse optics of its kind ever built. The optic is around 130 years old, weighs 10 tonnes and measures 7 metres tall. The Great Light served two lighthouses in its time, Tory Island off the coast of Donegal, and Mew Island off the Co. Down coast. The optic would have once produced one of the strongest lighthouse beams, ideal for landfall lighthouses. The Mew Island lighthouse was requested by the Belfast Harbour Commission as an important Aid to Navigation at the southern entrance to Belfast Lough, built at a time when Belfast was the world-centre of linen, ship-building and rope-making, and one of the most important ports in the world.