Two nights, several monumental projections on the city's most recognisable buildings: Notre-Dame de la Treille cathedral, the Voix du Nord building, and the Opera House. The logic of video mapping is to turn stone into living material: colour, movement, story projected onto buildings you thought you knew. The trail is on foot, freely, in no set order. People stop at the same spots, stand side by side without planning to. Something specific happens in this kind of gathering: collective wonder lowers people's guard. They comment out loud on what they see. Often towards someone they don't know yet.