A cave in Ireland ’s County Roscommon is believed to be the site of some in earnest spooky goings on . Oweynagat cave , also known as the Cave of the Cats , is said to be Ireland ’s " Gate To Hell " , a place that act as a portal to the otherworld each year on October 31 .

That belief date back around 2,000 years , and as local archaeologist and historian Dr Daniel Curley to theBBC , the transitional flow between autumn and wintertime brought with it a host of unusual , otherworldly characters .

“ Monsters and materialization would go forth , led by the goddess Morríghan , to produce a cosmos ready for wintertime , including birds with foul breather that would rifle leaves from tree diagram . local would stay indoors in awe of being dragged into the other world when the ghouls had complete ravaging the land , " Curley explained . " If you had to go outside you wore a costume and mask to look hideous . That manner you would be left alone and not drag into the otherworld . "

Dressing up asscarycreatures and heading out at Nox – sounds familiar , right ? And some believe that the Cave of the Cats could be the place of origin ofHalloween .

The pre - Christian fete of Samhain ( pronounced SAH - win ) was defend at Rathcroghan , the Ancient Capital of Connacht where the Cave of the Cats is found . It ’s now the large unexcavated Royal Site in Europe , with over 240 archeologic sites spanning 5,500 year of human history – from the New Stone Age through to the late medieval period . It ’s also home to28burial mounds dating back to the Bronze and Iron Ages and is described in medieval lit as one of Ireland ’s three key entombment sites .

Oweynagat , also known as the “ cave of Cruachan ” , is one of the famous site at Rathcroghan , not for its size or karst , but for its archaeological history .

“ It was regarded a malefic hell - like plaza full of terrify mythical tool and supernatural being , ” explain Joe Fenwick and Matthew Parks in the journalIrish Speleology . “ In the metrical Dindschenchas the cave is describe as the residency of the Morríghan , a pre - Christian goddess of warfare . Other early text associate it with sinister and brute pig , bird , cats and female werewolf . It is a place to be feared , peculiarly on the eventide of Samhain when the boniface of ‘ hell ’ are said to come forth from the cave . ”

Samhain may have made the leap into what we now know as Halloween when Irish immigrant traveled to the United States in the 1800s . A place where , to this twenty-four hours , masses navigate the Nox of October 31 in disturb costumes – though we ’re not trusted what Morríghan would ’ve made ofHeidi Klum ’s worm .