Fastnet Rock is a small slate islet rising about 30 metres out of the sea, several miles off the coast of Crookhaven - the home of the shore station for the lighthouse that stands on the rock. In the 19th century Fastnet was often referred to as the teardrop of Ireland, due to it being the last bit of land visible to Irish immigrants aboard America-bound vessels.
The impressive Fastnet lighthouse was built onto the north side of the rock 1904 to replace an earlier metal tower that stood at rock's peak, following an accident with a similar tower, on Bull Rock, which collapsed during a gale, which luckily resulted in no loss of life.
William Douglass designed the new lighthouse in such a way that waves are deflected when they hit the tower's sides - lighthouses that are built to this design are referred to as being wave-washed.
The tower is built out of giant blocks of Cornish Granite, which was carved ashore and shipped out to the rock piece by piece, gradually being assembled stage by stage, all whilst the optics and lantern were being built for the lighthouse at a factory in Birmingham, England.
Unlike the original tower, which had keeper's accommodation built to the side of it - which still exists today - keepers of the new tower lived inside the new lighthouse, with all of the furniture being built to fit the circular plan of the tower.
Construction and assembly of the lighthouse took 5 years and 2,074 stones were used, ranging from 1¾ to 3 tons.
Some features of Fastnet's design share similarities with features seen on many of England's offshore lighthouses; mainly Bishop Rock and Eddystone - this is probably because William Douglass was also notable for designing the current appearance of Bishop Rock lighthouse and oversaw the construction of the current Eddystone light. William's father and grandfather also built several of England's other offshore lights, including the Longships lighthouse.
Fastnet, like Bishop Rock, used a biform lens - essentially a lens with two tiers - this lens comprises of 4 panels; each one giving a steady flash every 5 seconds.
The lamp was first lit on 27th June 1904 and the old tower was de-constructed, leaving only its base, which was then used for the new tower's oil store.
The new tower is built to an unusual design, including two separate galleries; one bellow the lantern room - as is normal - and another a few metres below that.
Electricity replaced the original vaporised paraffin setup in 1969.
An explosive fog signal was fired from the lighthouse in reduced visibility until its replacement in 1974, at which point an electric fog signal was installed, which remained in place until 2011, at which point it was one of Ireland's last functional fog horns.
The lighthouse can be seen from Crookhaven by following the R591 to the end.
Crookhaven Lighthouse served as the shore station for Fastnet from 1854 until automation in 1989.