One of the most prominent features of the Irish landscape is the great multitude of megalithic sites which date back to the Neolithic. In this paper, I will attempt to demonstrate that the understanding of these sites in Ireland can be enhanced by referencing the native tradition, including the Irish word for the sites, sí, and the sí's powerful cultural tradition attested to throughout native Irish folklore, literature, onomastics, and traditional knowledge. In doing so, I will explore the difficulties and the potentials of interdisciplinary communication between archaeology and folkloristics, and the related issues regarding communication between official and unofficial discourses.