The immersive version of The Promise of Babylon turns the globe inside out. Instead of a world held at arm's length behind glass, the garden climbs the walls of the room and the viewer stands inside it, among roses and lilies and orchids, butterflies moving through the whole of it, everything in bloom and staying that way. The Hanging Gardens are the only one of the ancient wonders nobody has ever found. They appear in no Babylonian record, and what survives is description written centuries later by Greeks and Romans who had not seen them either: terraces sealed with bitumen, chain pumps hauling water into the air. Harris takes the idea rather than the site, and builds it in code, sensors and light.

The garden only moves because someone is there. Tracking picks up where each visitor is standing and how they are moving, and a physics system does the rest, so stems bend away as people pass, vines swing and settle, petals lift, butterflies scatter and regroup. The sound shifts with them. None of it is footage. It is calculated frame by frame as it happens, which means the state of the garden at any moment belongs to whoever is in the room, and no two people walk into the same one. The Dutch vanitas painters put flowers on the table to remind you that everything dies. This is the anti-vanitas: a celebration of life and living, and one that responds to you for as long as you stay in the room.