At the crossroad of contemporary art and urban anthropology, Petrichor is an installation and research protocol that investigates ‘the smell of the soil after the rain’. Taking urban soils as our guide and exploring how early attempts at studying them can speak to us today, we reflect on the place of soils and ecological processes in cities. As petrichor emerges in the fragile intermingling between soil and atmospheric processes, it leads us to consider how the ground and the sky, two entities that modern thinking about the city has tended to separate, may once again be brought into correspondence.