It was one of many made with stones to tell World War Two planes they were above Ireland.
The website Eiremarkings is reporting that there are approximately 85 of these signs built around Ireland but many have since disappeared or been taken apart.
The sign, one of around 83 created during the Second World War, was exposed for the first time in decades after a fire at Bray Head in Co. You can also see the number 8 under the EIRE writing indication the location of the post.
An Irish police air unit spotted the word Eire, which means Ireland, while surveying the damage caused by a fire on Bray Head.More news: Chelsea duo set for talks with Sarri
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The Defence Forces Air Corps noticed the landmark from above while assisting emergency services as they put the fire out.
This helped American bomber pilots navigate across the Atlantic. Being found on Ireland's east coast marks this new discovery as unusual, but there are many other examples to be found along the country's 3,200-kilometer (2,000-mile) coast - as plenty of Twitter commenters were happy to share.
As we read in a yarn from RTE, the sign was made from stone, carved into the ground by local volunteers.
Measuring a massive 12 by 6 meters (39 by 20 feet), more than 80 of these markers were literally carved into the landscape during World War II - and then built with up to 150 tonnes (165 United States tons) of whitewashed stone set in concrete.