Of particular interest to us though is the famed Cave of Cats or Oweynagat, south-west of Rathcroghan Mound. It is a souterrain beneath an old road leading into a dark, narrow limestone cave. This cave was believed to be a gateway to the otherworld with many creatures emerging that generally caused havoc across the country. The name Oweynagat means “cave of the cats”, which could refer to the large wild cats which the Ulster champions must fight in the tale of “Bricrius Feast“.

Cruachan seems to have heavy associations with the feast of Samhain, as it was during this time that the Irish believed that the prehistoric graves from before their time opened and their gods and spirits, who dwelt inside, walked the earth. The emerging of creatures from Oweynagat would be part of this belief. A legend based on this is “The Adventures of Nera“, in which the warrior of the title is challenged to tie a twig around the ankle of a condemned man on Samhain night. After agreeing to get some water for the condemned man he discovers strange houses and when he finally gets him some water at the third house, he returns him to captivity only to witness Rathcroghan’s royal buildings being destroyed by the spirits. He follows the fairy host to the síd where he meets a woman who tells him that what he saw was a vision of what will happen a year from now unless his mortal comrades are warned. He leaves the síd and informs Ail ill of his vision who then has the Side destroyed.