The faint light of a small torch twinkles in the entrance to Oweynagat, at Rathcroghan, close to Tulsk in Co Roscommon. When it is switched off, the dark is beyond pitch black below and spookily silent.

I’m sitting in the narrow, slightly muddy entrance to the so-called ‘Cave of the Cats’, the birthplace of Halloween, also known as ‘Ireland’s Gate to Hell’ looking at an Ogham inscription, the earliest form of writing in Ireland. This job can take you to some unexpected places, and this one is certainly up there.

While I had passed this area many times on journeys west, I had never stopped or realised I was in the midst of the rich farmland landscape of Cruachan Aí that boasts over 240 archaeological sites, 60 alone which are national monuments spanning over a timespan of 5,500 years.

Dr Daniel Curley, manager of Rathcroghan Visitor Centre, smiles as he describes the area as an “archaeologist’s dream.”

It has several millennia of “unparalled evidence of settlement and ritual activity” in Ireland, if not Europe, he says, with ringforts, royal burial mounds, Stone Age tombs and massive linear earthworks all spread over 6.5 sq km of land in Connacht’s prehistoric royal capital.

For a place like Oweynagat, which is so important at this time of the year, it’s easy to miss and quite hard to find. Walking up a typical rural boreen, there is little sign of modernity and no clue to what lies ahead.

Origins of Samhain tour

Greeted quite appropriately given the area’s moniker by two cats, I walk into an ordinary-looking field, which is privately owned by a farmer from Sligo who allows visitors to the Rathcroghan centre in small groups to access it. In the middle of a long hedgerow, I spy a strange-looking opening emerging from the earth.

This is the entrance of Oweynagat, a “special spot”, according to Daniel, who is giving a preview of the Origins of Samhain tour which is booked out every year.

Setting the scene, he explains that Rathcroghan was important for all of society at the pagan pre-Christian festivals of Imbolc, Bealtaine, Lughnasadh, and Samhain and it was a place of ritual gathering.

“The last festival of the year marks the transition of autumn into winter, and that’s the festival of Samhain. That’s the point when you brought your livestock home,” explains Daniel.

Depending on how bountiful the harvest was, farmers then had to make a decision on how many cattle to keep for the winter period. Naturally enough, then, Samhain was always marked by a feast to consume the excess.

Samhain in particular was celebrated at the Roscommon site with activity focused on an elevated structure, possibly a wooden temple on the nearby Rathcroghan mound, which would have been lit up for the occasion.

It hosted the ‘Electric Picnic’ of its time, a mass gathering and celebration of the goddess of the land, Medb, before the crowds would disperse off elsewhere.

Here is known as the birthplace of Samhain, according to Daniel – a time of year when it was believed the invisible wall between the living world and the otherworld disappeared and spirits could walk freely among the living.

“In the feasting halls on Samhain night, people were regaled with stories of the monsters and creatures and manifestations that emerged out of the otherworld from this cave on our mortal plain in order to create the world ready for winter,” he explains.

Giving a whistle-stop tour of some of the very visceral mythology and stories associated with this hidden part of Roscommon, Medb looms large. Her son Fráoch was brought to the cave when he was mortally wounded by a water creature to be brought back to life.

Then there is the Mórrigan, the shape-shifting goddess of war, and the many creatures who came out of the caves on Samhain night.

“Some of the stories talk about a flock of red birds whose breath is so fowl it takes the leaves off the trees coming out on Samhain night. They talk about three giant wild boars that every piece of vegetation they touch withers.

“They talk about female werewolves, three-headed monsters, giant cats, which is part of the naming of the monument, and armies that all emerge out of this otherworldly space.”

Trick or treat

Dr Curley is keen to stress that it is not just his theory that Halloween originated here; it’s borne out of strong evidence.

“We have a manuscript tradition here that’s over 1,000 years old, and the weight of stories that relate to Halloween being associated with this cave is greater than any other location on the island. It’s the stories themselves that are rooting themselves in this place.

“They are telling us that this place is synonymous with Halloween; it is representative of Halloween (Samhain) and the access point between our world and the other world being opened and the Mórrigan (the goddess of war) allowing for the process of winter to take hold,” he explains.

Then she returns all the “catatonic energy back into the otherworld at the end of the night. And that’s where we get the bones of Halloween as it is.”

The otherworld wasn’t hell, he contends either, but a “proto-paradise” of Tír na nÓg, where time stands still and people don’t grow old. However, it does have a dark side at Halloween, and lots of the traditions we still hold can be traced back to these times.

“If you look at the Folklore Commission, they record stories whereby you did not leave your home after dusk (on Samhain night), but if you did leave, you did so before dusk and in costume, and that’s where we get the origins of the costume. Disguising yourself so you’re not apprehended by the manifestations that are out there.”

The idea of trick or treat or feasting in advance of winter has its origins here too.

Sometime in the early medieval period, the karst limestone cave was added to by a manmade entrance with Ogham writing, from the 4th to the 8th century, referring to the earlier stories.

It also became very much associated with warriors who defeat creatures coming out of the cave or warriors who go into it to face their fears. So, Daniel argues that “it is a place of testing, a place of initiation, a rite of passage”.

Sitting in the tight entrance, it’s easy to see why. Due to health and safety, it is no longer possible to go right down into the cave, but with the lights off in the entrance, you get the feeling of being discommoded immediately.

Given that overseas visitors to Rathcroghan make up 45% of people through the doors every year, what do they make of it all?

Interestingly, many start enquiring about the tour in January, and quite a few make Rathcroghan and the cave their very reason for coming to Ireland, Daniel says.

“They love the fact that you can access part of not just Irish archaeology but it is a stitched in part of mythology in our early literature,” he adds.

Looking ahead, he is excited about opening a new 13km walking trail through Rathcroghan’s main sites in conjunction with landowners later this year. He is also continuing his work with local farmers on protective measures to preserve the area’s unique heritage.

“The word is spreading, but at the same time we have to pay deference to this place,” Dr Curley, who has just published his first book observes. “It’s been here for thousands of years, and I want it to be here for thousands of years after I’m gone and the landscape with it.”