Megalithic structures is a broad category, covering everything from portal tombs and passage graves to standing stones and stone rows, all generally dating to the Neolithic or early Bronze Age, roughly 4000 to 1500 BC. What exactly survives at Askillaun, whether a collapsed chamber, an upright stone, or something more substantial, is not currently documented in any available public record.

Askillaun itself is a small, sparsely inhabited island in Clew Bay, that famously island-studded inlet on the Mayo coast. The bay's drumlin islands, rounded hills of glacial till now partially submerged by post-glacial sea level rise, were settled and farmed from the Neolithic period onward, and megalithic remains are not unusual across the wider region. The presence of a recorded megalithic structure on Askillaun places it within that longer pattern of prehistoric activity along this stretch of the west Mayo coastline, even if the specific character of the monument remains obscure.