Research into prehistoric buildings in northwest Europe has identified the ubiquitous use of turf. The study first introduces direct and proxy evidence for the material’s detection in the field, then analyses individual case studies to demonstrate how this locally available and renewable material shaped buildings and building practices. Turf, grown and sourced on or near a site, ties buildings to their landscape, while creating flexible shells that can shift as needed, metamorphosing built space and volume accordingly. Turf’s capacity to then compost and regrow embeds its buildings into a prehistoric circular economy that interweaves dwellings, people, animals, plants, soils, and nutrients into a holistic understanding of a “curated” rather than a “built” environment – an architecture borrowed from the soil to which it can return. The characteristics of turf blocks as a malleable and arguably metamorphosing building material call for a rethink of turf architecture, not resulting in static products but in ongoing circular processes. This new concept operates within an extended lifecycle of houses, not as in traditional approaches from birth (built) to death (abandoned), but within a cyclical, cradle-to-cradle approach. An experimental training project now translates this prehistoric cyclical model into modern sustainable turf building practice to demonstrate its potential for positive climate action today.