In recent decades, human civilisation has experienced a profound tipping point which, after millennia of the opposite, switched the balance of our populations from the countryside to the cities. The urban has come to define modernity to the degree that those of us who live in metropolises experience them as indispensable and singular symbols of what it means to live now. But the city’s tremendous achievements—its consolidations of technology, culture and efficiency—can extract costs of which we must remain ever mindful. From the wear and tear of particulate matter on our bodies to rush-hour transport congestion to such unforeseen effects as the precipitous decline and alteration of birdsong, the city is an entity, an organism, a concept that presents relentless challenges to the policymakers, architects, engineers, artists and—above all—the sundry residents who confront it. This month, we celebrate the consciousness-raising task of examining ways to exist within and appreciate the city, and to rise above its flaws and inequities to explore its joys and the possibilities of its history and future.