Our participation last year in the attempt to collectively buy one of the tallest towers in the city of Antwerp; ‘Den Oudaan’ or the city’s police tower, led to very remarkable insights for the EULER project. We discovered that the key of our collective action was the ‘openness’ of the process. This openness is in big contrast with the conventional process of developing real-estate, which is perceived as ‘closed’. It was because of the open and transparent character of the process an enormous potential of skills amongst citizens emerged. While the initial ‘call’ (on social media and in the press) of our collective was not more than ‘let’s buy this building together’, people responded to this call by sharing their ideas for the future of the building and started offering all kinds of expertise – and even money – to realise those ideas. This phenomenon showed that citizens have not only the appetite to develop buildings and sites – and in that way influence their living environment – they are even willing to share their knowledge and put in their own skills and expertise for the realisation of their future urban environment.