The lighthouse stands 27.7m (91ft) high and was erected in 1809. The simple, dignified, and whitened tower is dominated by its atypical cornice with modillions (projecting brackets). Part of the grouping of buildings is an inverted fog-bell weighing 2.5 tons and an ingenious arrangement whereby, when the frequent fog or low cloud obscured the light, a small clockwork operated (3.05m (10ft) square) lantern mounted on wheels was lowered down a quarry-like railed incline to within 15.2m (50ft) of the sea. Only the bed of the incline survives today on eth north side of the rock. A compressed-air horn was later fitted on this site and this in turn has been replaced by the fitting of an electronic fog signal.

Event and Historical Information:
The South Stack lighthouse occupies a site of dramatic grandeur on the 30.5m (100ft) summit of a small island off the north-west of Holyhead Island. During the building operations a cable way was used to carry materials from the mainland to the island and in 1828 this and an early rope bridge were replaced by a suspension bridge (at a cost of £1,046), which in its turn has been succeeded by a rigid tubular lattice-type bridge. Both lie at the foot of a spectacular descent of 400 stone steps. The engineer and builder of the tower were Daniel Alexander and Joseph Nelson respectively. Nelson later designed several more lighthouse towers on the west coast of Britain. The cost was £11,828 exclusive of the attendant dwellings also built by Nelson. Revolving Argand lamps and reflectors were added in 1818. An historic Admiralty chart dating to 1846 notes that the light revolved every 2 minutes at 20ft height and that there was also a low red light. In 1874 the white-painted tower was heightened and a new lantern fitted. The builder and engineer of this early (1832) traveller-incline for the clockwork operated lantern was a Hugh Evans. The lighthouse was converted to automatic operation in 1984 and is operated from the Holyhead Control Centre. The former Trinity House Fog Signal Station at Holyhead North Stack has now also been sold-off.

Sources include:
English Lighthouse Tours 1801, 1813, 1818, ed. D. Alan Stevenson, 1946.
Hague, D, 1994, Lighthouses of Wales: Their Architecture and Archaeology, pg57-8
Historic Admiralty Chart 1684-A2, RCAHMW Digital Collections sourced from UK Hydrographic Office (published 1846)
Report of the Select Committee on Lighthouses, 1834.
Royal Commission Report on Lighthouses, 1861.

Maritime Officer, RCAHMW, December 2008