The archaeological discoveries made on the M3 Clonee–North of Kells motorway scheme in County Meath have been widely published in the media in recent years.Yet the insights into our past from an extensive programme of research, geophysical survey and archaeological excavation have been comparatively neglected in public debates. The scale of the M3 scheme as an infrastructural development, travelling 60 km north–south through County Meath from the border with Dublin to the border with Cavan, and covering an area of approximately 700 ha, has resulted in an archaeological project of unprecedented scale. In particular, the large-scale archaeological investigations carried out on behalf of Meath County Council and the National Roads Authority in advance of the M3 scheme comprise the most intensive investigations of aspects of the archaeological heritage of Meath ever carried out. All of these archaeological discoveries, ranging in date from earliest prehistory to the post-medieval period, will now be analysed, studied in scientific detail and published in a range of formats, but already it can be seen that many of the individual excavations will be of some significance in interpreting past lives and times in the Irish landscape. This paper focuses on how this work was carried out within an archaeological research framework and on the discovery of a new National Monument at Lismullin.