Cities are pervasive and they are some of the most powerful ecosystems of the Anthropocene. They have been around for almost 10000 years, and by the year 2050 most humans will be living in a city. Although it is known that cities have an impact to different scales, from the very local to the whole Earth System, its implications are far from being understood. Studying cities as organismic systems has been a productive strategy and favourable to complex adaptive systems analyses. However, the organismic view is to a great extent metaphorical, focusing exclusively on human activity, instead I argue for an approach that actually considers life processes as constitutive to them. In this extended abstract I suggest a conceptual framing for a synthetic approach to cities in which life processes are paramount for their understanding. Specifically, I will focus on two aspects: 1) the human-teleological component of cities and 2) the role of life processes organisationally closing the city, and bringing forth a self-generated unity and identity and the conditions for its own evolution. I believe that due to the increasing interest of the ALife community in tackling social issues, ALife unique insights and methods can be of great value in understanding cities and dealing with the social-ecological challenges they pose. A definition of cities from a synthetic perspective can help the ALife community to put into action its epistemic arsenal.