A mega-event is a replicant: local copy of a global model. The European Capitals of Culture (ECC) is an annual mega-event, currently usually held in two European cities. This paper argues it has three particular dimensions, recognisable from the European Unions policy. First designed to articulate a European identity, it has been a mover for local urban transformation and city-branding, and later participation. The policy projects Europe as family of cultures, which suggests attention for a particular ECC year, when the old Saxon fortress town of Luxembourg hosted the title together with the former Saxon fortress town Sibiu of Romania, which joined the European Union only the same year: 2007. The article asks, what are the limits of the urban effects of the three dimensions of the European Capitals of Culture, using as a method urban art interventions for investigating the limits and potential spatial effects of the ECCs and the extent of the diffusion of institutional elements.