South Stack Lighthouse was first envisaged in 1665 when a petition for a patent to erect the lighthouse was presented to Charles II. The patent was not granted and it was not until 9th February 1809 that the first light appeared to mark the rock.

There was a gun emplacement and barrage balloons guarding the area during World War 2 and in the foreground is a relic from those days.
The Dublin Ferry in the background.

http://www.trinityhouse.co.uk/interactive/gallery/south_stack.html