This article presents major discoveries from a new campaign of large-scale multi-method geophysical surveying, focused on Navan Fort and its environs. Alongside a re-appraisal of excavated evidence, it offers a new model for the evolution of Navan. The large earthwork now known as Navan Fort sits alongside other iconic monuments such as Tara, Rathcroghan, Knockaulin and Cashel as one of Ireland’s so-called provincial centres. Historical texts imply that these Iron Age complexes became enduring symbols of power for early medieval societies, and royal centres for overkings. These references, alongside the incredible scale of these landscapes, have encouraged intensive research, but only recently has non-invasive survey begun adding new data and facilitating new interpretations. Prior to the present study, discussion of Navan Fort was limited to the results of small-scale but iconic excavations. These new discoveries significantly change understandings, adding spectacular new monumental phases, and facilitating re-assessment of Navan’s role within both later prehistoric and medieval society, as well as of the nature of ceremonial landscapes and their role in developing sacral kingship in northern Europe.