If you trace a simple graph showing percentage of the world’s population living in cities over the past ten thousand years of post-ice-age civilisation, the line moves from almost zero to majority urbanised in just three centuries starting in the seventeen hundreds, and by the end of the current century to something approaching one hundred percent urbanised. Map the same line over the two hundred thousand years since modern humans first emerged in Africa and it becomes a ‘step’-function: for most of history it is flat at almost zero and then suddenly a transition to almost one hundred percent in such as short space of time that the transition appears as a vertical line. The twenty-first century has been called the ‘urban century’ for good reason. In it we will reach a point that has never been reached before, with the vast majority of humans freed from the tyranny of subsistence farming and working in urban jobs that one way or another connect with each other across the globe. The process is the culmination of what, looking back, has been an inevitable phase change in social evolution, which although beginning in the Iron Age, took only about zero point one-five percent of human history to achieve. What will become of us in this new world? The twentieth century made commonplace the one to ten million people city. The twenty-first century will be known for the ten to fifty million city and by the last quarter there are likely to be multiple fifty to one hundred million cities. Will life carry on as usual as cities get bigger and denser? What will become of us as an entirely city-dwelling race? The Future of Cities is twelve three-minute films provoking speculation about such questions based on what we know now. Each film focuses on a theme that is practically significant, theoretically rich and existentially important to the future of civilisation. Each has links to research currently or recently undertaken in HKUrban Labs at the University of Hong Kong’s Faculty of Architecture. The films do not promote specific research projects. They promote awareness and discussion about big issues being addressed by HKU researchers and our partners around the world. And yes, they are influenced by the location of much of our research. Hong Kong is at the epicentre of the world’s greatest ever urbanisation experiment. It is also one of eleven cities in what is now being called the Greater Bay Area (GBA) of the Pearl River Delta: an ultra-dense polycentric city region connected by high speed transport corridors. Unofficial population figures make GBA the first one hundred million strong city region. What can we learn from it?