Western democracy has always been anchored by the idea of a public space where people gather to share ideas, mediate difference and make sense of the world. When Facebook blocked Australian users from viewing or sharing news in 2021, it sounded the alarm worldwide on our growing reliance on global tech companies to fulfil this critical role in a digital world. Facebook's hostile act, constituting a very real threat to participatory democracy, was a direct response to government attempts to regulate Big Tech's advertising monopoly and to mediate its impact on public interest journalism. The conflict sparked a new sense of urgency around the growing movement to imagine alternative digital spaces that operate in the public interest rather than simply for a commercial bottom line. Can we create sustainable media models to help us tackle society's problems? Can we engender a civic platform built on facts and civility? Can we control the power of our data and use it to promote the common good? The Public Square Project draws together leading tech scholars, industry experts, writers and activists to chart a path towards a public square worthy of the name.