For the third time since I started my position at Macquarie University, I have delivered a guest lecture in the Sustainable Urban Regions postgraduate course. In this lecture, I discuss the rise of the ‘platform or “sharing” economy’ and the consequent proliferation of unregulated tourist accommodations in cities. Drawing upon the work that I have done during my PhD, I talk about Airbnb’s impact on local housing markets. But I also talk more generally about the idea of “overtourism” and the consequent politicization of tourism from below. The guest lecture was entitled “Cities, tourism and the sharing economy”, took place on 21 May and was attended by a wonderful audience of postgraduate students. I enjoyed the following discussion very much!