This remarkable Bronze Age fortress consists of three massive concentric stone ramparts that follow the natural contours of the hill, creating an impressive defensive structure that stretches for 2.1 kilometres. The outermost wall encompasses roughly 11 hectares, whilst the innermost enclosure, standing up to 1.5 metres high and spanning 6 to 9 metres wide, protects a sacred space of less than a hectare where important ceremonies and gatherings likely took place around 1000 BC.

Archaeological investigations by the Discovery Programme between 1992 and 1994 revealed the sophisticated engineering behind this ancient stronghold. Each rampart was cleverly positioned along natural limestone terraces, amplifying their apparent height and creating a formidable series of barriers. The builders incorporated staggered entrances that forced visitors to follow a winding path around the hillside, whilst the middle rampart, reaching heights of 3.5 metres in places, featured an intriguing rectangular chamber built directly into its structure. Radiocarbon dating suggests the entire complex was constructed as a single ambitious project over approximately ten years during the final decades of the tenth century BC.

The hillfort contains several later monuments that speak to its enduring importance through the centuries. A cairn marks the highest point within the inner enclosure, possibly serving as a focal point for Bronze Age rituals. Various cashels, or stone ringforts, were built atop and around the ramparts during later periods, including one that caused considerable damage to the southwest section of the middle wall. Between the inner and middle ramparts, archaeologists identified the remains of three unenclosed roundhouses, suggesting the site supported a small resident population. Now protected as National Monument 649, Mooghaun stands as one of Ireland’s most significant prehistoric fortifications, its weathered stones bearing witness to three millennia of human history.