Slieve League in Co. Donegal boasts some of the highest sea cliffs in Ireland, towering 600 metres above the Atlantic Ocean. It's a popular spot for hillwalkers because of the famous One Man's Pass, a short section of ridge with dizzying drops on either side and just wide enough for a single person to walk along.
The tower you can see is part of the network of signal stations built around the coast during the Napoleonic wars to warn of an invading fleet.
There are remains of an early Christian monastery on the mountain and it's believe the monks sailed from the nearby village of Teelin to Iceland, landing there before the Vikings settled in the 9th century.
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