Opinion: Oweynagat is a cave linked to many colourful tales in Irish folklore, especially around Halloween
By Gary Dempsey, Galway Mayo Institute of Technology.
Hidden along the side of a small county cul-de-sac in Co Roscommon is a stone lined underground structure called a souterrain, constructed between the 7th and 12th centuries. It's located within a wider region known as Rathcroghan which comprises over 250 archaeological monuments.
But what makes this particular site stand out from others sites? Well, it was built above a natural cave and was once known as "Ireland's gate to Hell", which would open during the festival of Samhain.
Halloween is the modern celebration of Samhain, a time of year when it was believed that the veil between this world and the 'Otherworld' was weakened and spirits could walk freely among the living. The Otherworld is sometimes depicted as a land of plenty, where time passes at a different pace. Sometimes better known as Tír na nÓg, it also has a dark side, and once a year on Halloween that dark side emerges from Oweynagat (Cave of the Cats) in Co Roscommon.
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From Cruachan Aí Rathcroghan, Elaine Conroy talks about Oweynagat, the Cave of the Cats
A natural fissure in the limestone which covers this region of Roscommon, the cave is quite narrow and extends for 37 metres. The natural entrance was enclosed in medieval period by a Souterrain. The site was recorded in a 3D model by the Discovery Programme in 2014 as part the Ogham3D project.
There are two Ogham stones located at crossing points with the souterrain. One stone reads ‘VRẠICCI/ MAQI MEDVVI’ or [The Stone] 'of Fróech, son of Medb', evoking associations with Queen Medb, who led the armies of Connacht in the Ulster Cycle tale, Táin Bó Cúailnge (The Cattle Raid of Cooley).
The name Oweynagat likely originated from a side tale of the Ulster Cycle. The tale Bricriu’s Feast tells how three heroes, Lóegaire, Conall Cernach and Cú Chulainn, are tricked into fighting over the Hero’s Portion by the mischievous Bricriu. To settle the argument, they leave the feast and head to Rathcroghan to seek out the judgement of Ailill, the husband of Queen Medb. The heroes are given lodgings and fed for three nights, as was the custom in ancient Ireland. On the fourth night, the food was delivered to them as normal and, as they sat down to feast, three ferocious cats were let loose form the Cave of Crúachu. Both Loegaire and Conall fled, but Cú Chulainn faced down the cat and was announced the hero by Medb.
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From RTÉ Radio 1's Almanac of Ireland, Manchán Magan pays a visit to Oweynagat
A second tale within the Ulster Cycle suggests that the ‘Otherworld’ could be entered through the cave on the night of Samhain. The Adventures of Nera tells the story of Nera who carries the corpse of a recently hung man to find a drink of water. Upon his return to Rathcroghan, Nera sees that it has been burned and all within killed. He follows a group of men back to the Cave of Cruachan, emerging in the ‘Otherworld’. While there, he marries a woman and must bring the King a bundle of firewood every day. He learns that Rathcroghan was not destroyed, and returns to warn Medb and Ailill what he has seen. The tale concludes with a section about a cattle raid from the otherworld.
A local version of this ending records how a woman who catches the tail of a runaway calf is dragged into the cave only to emerge at the Caves of Kesh in Co Sligo. This story was recorded in the 18th century, but has been retold by each generation as if it was something that happened within living memory..
In a section of 12th century placename lore, the Battle of Mag Mucrama, a host of creatures are listed as coming from the Cave of Crúchcu ‘Ireland’s gate to Hell’. The creatures included a swarm of three headed creatures that laid waste to Ireland; saffron colour birds, that laid waste to the crops of Ireland and a hoard of pigs who multiplied each time they were counted and ate everything in sight.

The cave is located on my paternal grandparent's land. Their house, built only a few metres from the entrance of the cave, was a local rambling house, where people would gather to tell stories and sing songs. One such story was told about the night my aunt was born. During the birth, a storm arose and the screams of cats could be heard coming from the cave. Fearing the worst, my greatgrandmother took her new granddaughter to the church to be baptised that night, at which point the storm stopped and the cats ceased screaming.
Rathcroghan is a landscape rich in archaeology which has inspired generations of story tellers. Whether these are tales recorded in ancient medieval manuscripts or local folk stories, it is clear that there is a sense that Halloween was a time when Oweynagat could open the gates of hell or become an entrance to a magical world.
Oweynagat is located on private farmland and is protected under the National Monuments Act and Annex I of the Habitats Directive. To arrange a visit to the site, contact the Rathcroghan Visitor Centre in Tulsk, Co Roscommon.
Gary Dempsey is a digital heritage expert who lectures in Design and Heritage Studies at Galway Mayo Institute of Technology.
The views expressed here are those of the author and do not represent or reflect the views of RTÉ