Banba's Crown in Co. Donegal is the very northernmost point of the Irish mainland. Malin Head is a little further west and a kilometre or so south. You can see a Napoleonic watchtower sitting on the hill.
The image was made right around the autumnal equinox. At this time of the year, the sun rises directly in the east and sets directly west, and so we're looking straight west in this photograph. The northernmost point of Ireland, therefore, is the rightmost collection of rocks in the photograph.
When there is strong solar activity, the Northern Lights can be seen from Donegal and Banba's Crown becomes very crowded with people hoping to catch a glimpse of this rare phenomenon.
(You can buy a print of this photograph here: https://buff.ly/2vG4dlJ)