Rathcroghan is one of Ireland’s most extraordinary ancient landscapes, home to over 240 monuments — from burial mounds and ringforts to vast ceremonial earthworks — with a history stretching back thousands of years.

This was the seat of the legendary Queen Medb of Connacht, and tradition holds that here the veil between the living and the dead grows thinnest.

A short distance from the great mound lies Oweynagat, the Cave of the Cats. At first glance it appears to be just a dark opening in the earth, but in folklore it is far more — a gateway to the Otherworld.

Early traditions describe it as a place of fertility and divine power, while later Christian writings cast it as nothing less than Ireland’s “Gate to Hell.” The battle goddess Mórrígan is closely tied to the cave, taking the form of crow, wolf, or eel to foretell bloodshed and doom. Tales tell of Queen Medb summoning monstrous cats from its depths to challenge the warriors of Ulster.

Medieval lore claims that each Samhain, when the veil was at its thinnest, the cave split open and unspeakable horrors poured forth: red-eyed pigs, spectral birds, and three warriors who brought disease and ruin until they were forced back below. On those nights, spirits were said to walk among the living, and locals stayed indoors or wore disguises to avoid being taken into the Otherworld — a custom many see as the root of our modern Halloween.

Even today, Oweynagat is not for the faint-hearted. Visitors must crouch through a narrow tunnel until daylight vanishes into stone. Above the entrance, a weathered inscription still sparks debate — many believe it names Fraech, son of Medb, perhaps the oldest written trace of her legacy.

Those who brave the chamber report sudden chills, the feeling of unseen eyes, and strange noises in the dark. Paranormal investigators have captured guttural growls, sharp knocks, and whispered voices — sounds too deliberate to dismiss. Tradition insists that anyone entering should leave an offering, lest something follow them home.

On Samhain night in particular, the cave is said to stir. Locals whisper of shifting shadows, fleeting figures, and voices rising from the depths. One farmer claimed he heard the thunder of hooves and the clatter of chariot wheels beneath the ground — an army rising in the dark. Others speak of glowing-eyed cats slipping through the gloom, reminders of the Otherworldly beasts that once emerged when the veil was at its thinnest.

In October 2023, a team of paranormal investigators visited the cave in the days leading up to Halloween. After squeezing through the narrow entrance, they took a series of photographs from deep within the cave. Only after leaving the site did they notice something disturbing—one of the images appeared to show a female figure lurking in the shadows. On closer inspection, the figure seemed to be striding—perhaps even running—toward the camera.