In contrast to the old paradigms that opposed a Mediterranean of cities and states to a Celtic Europe of villages and tribes, new archaeological research now depicts the end of the Second Iron Age as a complex and dynamic world, in which state structures developed and a characteristic urbanism germinated. Following the publication of the volume Oppida. Cities of Celtic Europe, published by the journal Desperta Ferro Archaeology and History, the symposium brings together a dozen researchers to analyse the keys to these phenomena in different areas of the Celtic world – demography, society, urban planning, identities and warfare – from the Iberian Peninsula to Gaul, in the period before the intervention of Rome.