Smart cities are characterized by the close integration of ICT devices and humans. However, the vast majority of current deployments of smart technologies relies on sensing devices collecting data and data mining techniques squeezing little meanings out of them. Nevertheless, we believe that citizens integrated with ICT technologies could collaboratively constitute large-scale socio-technical superorganisms supporting collective awareness and behaviours. This paper clarifies our vision on urban superorganisms, identifies the key challenges towards their actual deployment and proposes a prototype architecture supporting their development.