The Rathcroghan complex is a four square mile archaeological region located in Co. Roscommon, Ireland. It is noted for being one of the richest archaeological areas in Ireland with over 200 recorded monuments centring on the Celtic Royal Centre of Rathcroghan (Cruachan).
The area is located within a complex archaeological region with a history stretching back over 5000 years, with everything from burial monuments, pre-historic residential sites, royal places, temples and the entrance to the Otherworld (Oweynagat).
Today the region is mostly agricultural land. All that remains of this once great royal landscape is a series of field monuments and mounds which mark the location of the ancient sites.
The central Rathcroghan site is the only site in the complex freely open to the public (tours to other locations are arranged through the Rathcroghan Visitors Centre @ Cruachan Aí). This site is a broad flat-topped circular mound with a base of 90 meters and a height of 5.5 meters, sloping ramps on the east and west give access to the summit, on which there are traces of a small mound. Once thought to be a natural feature shaped by man to its present form, archaeological research has shown that it is in fact a man-made structure sitting on natural glacial ridge.
The mound was once the location of a large earth and stone structure which would have stood 15-20 feet high. The central stone monument was surrounded by a series of spiral henges and enclosed by a wooden palisade held in place by a revetment wall. A wooden passage extending to the east provided the only access to this monument which was the focal point of a spiritual and kingship tradition associated with both the Goddess Medb (sovereignty) and the Morrigan (Battle, Strife and Fertility).
While there has been no excavation of the mound, geophysical surveys have revealed there to be a second temple site beside the monument and a possible passage and chamber located beneath the site. It is unsure what this feature may represent at the present moment, but it been strongly suggest that the mound hides a passage tomb, similar to the Mound of the Hostage at Tara or Newgrange.