“A Grain of” is an art installation made by the authors: a small cube (25 x 25 x 25cm) of custom-made matter, sitting on a plinth, emitting sound from within. Its underlying idea is to take a “grain” from a dense, contemporary urban space and translate it into an art installation that makes the city experienceable for the audience. This small cube holds some of the material and sonic ecology of the city from which it stems embedded in it. In the accompanying paper, the authors describe the technical processes that they have used to sample and reinterpret the city’s material and sonic ecologies, including Atomic Force Microscopy (AFM), 3d printing, field recording, and sound synthesis. They offer some theoretical notes towards the grain of the city in order to investigate how this process of technical translation produces an experience with affective, poetic, and speculative potential. They argue that this experience lets its audience critically rethink the old enduring binaries between natural and artificial or between the city and nature.