The Possible is about the future of buildings and cities and the ideas and innovations that can help them function better. In this issue we explore the limits on city density, the future of education, next-generation construction materials and whether we’ll ever be able to design a totally recyclable building. Chicago architect Gordon Gill, designer of the 1km-tall Kingdom Tower, talks about his responsibilities and regrets, and psychologist Naomi Shragai investigates what’s really happening when project teams collaborate. In our Connected Thinking section, contributors contemplate how drones will shape development in Africa, the seismic threat to Asia’s megacities, hospital design in a post-antibiotic world, how architects can ensure the wellbeing of site workers thousands of miles away, and why engineers should read more philosophy. It was designed by Supermassive and the cover illustration is by Noma Bar.