The beautiful tower of Fastnet lighthouse replaced a cast iron lighthouse built in 1854 and considered unsafe.Fastnet is the tallest and widest rock lighthouse tower in Ireland. It was a monumental achievement when completed in 1904. Each of the 2074 stones, weighing from 1,5 to 3 tons are dovetailed into those around it, bonding the structure into a virtual monolith.The tower is 54 meters height, the light is a white flash every 5 second with a range of 27 NM, the fog signal give 4 blast every 60 seconds. The radar beacon is the Morse letter "G " on vessel's radar display. The lighthouse been converted to electric in 1969 was automated in 1989.