There is an article floating around the internet again that has over 6.8 thousand shares.
The article talks about an archaeological find that shows that the Vikings had more than one stronghold in Ireland. This is actually well known.
The remarkable thing about this find, is that the site has not been damaged by roads and buildings, but is a "virgin" site.
The knowledge, however, that the Vikings were in Ireland and had set up strongholds, is not new in any way. The capital city of Ireland, Dublin, was actually set up by the Vikings, or Ostmen as this group was known.
Taken from WeselyJohnson.com:
"The first raids in the British Isles was in 793, when the great monastery at Lindisfarne was sacked. In Ireland, Rathlin island monastery was burned by the Vikings in 795. Other prominent monasteries that were attacked included Holmpatrick, Inishmurray, Inishbofin and Sceilg Mhicil. Sceilg Mhicil's abbot died of thirst as a Viking prisoner. St Colum Cille's great monastery at Iona was burned in 802. For the next 30-40 years, the Vikings engaged in hit-and-run raids where they landed a small number of ships at a settlement, spent a few days pillaging and burning it before heading back to Scandanavia to sell their booty. The Vikings were after two types of booty - riches and slaves - which they carried off to sell. They soon found that the monasteries were the richest sources of both goods and this is why monasteries suffered so much. However, the Vikings also attacked a lot of grád Fhéne (commoner's) dwellings."
As we can see in the map attached, the Ostmen had great influence and several strongholds in Ireland. They actually controlled Dublin for nearly three centuries.
The original article was written in 2011, but somehow they are going around again.