In the northwest of France, raw earth has been broadly used, especially in Brittany where cob dwellings have been built since the sixteenth century. Today, cob buildings represent 20 % of the built heritage on this territory (Bardel P., Maillard J-L. 2009). The cob technique is also found in the Vendée marshes, where squat dwellings (“bourrines”), dating back to the fourteenth century, bear witness to the use of local, natural resources (Patte E., Streiff F. 2006; Bonnet S., Alzeort D, Poullain P. 2021). Between these two well-documented earth-building territories lies the Guérande Peninsula where earthen heritage, until recently little-known and neglected, has become the object of study.As a result of several inventories undertaken by earth-building professionals, a part of this heritage has been recorded and mapped (Hilton A. 2016; Miranda Santos M. 2016; Humblot D., Josset F., Marquis B. 2018). Two main research methods have been used: · a general audit of the specific areas of the peninsula where earth buildings exist,· a targeted audit of certain villages and their buildings.This latter entailed a comparison of historical maps with current cadastral maps, followed up by on-site verification.Following this inventory work, a sense of the nature and extent of local earthen heritage is beginning to emerge, feeding synergies with renewed local interest in earth construction. The Maison Neuve eco-district in Guérande presents a clear example of this: its objective is to reuse several thousand tonnes of its own site-excavated earth in earth-building projects over the next 5 years. The results of the inventory work helped this local project to understand the nature of the earth available and the different relevant earth-building techniques. The inventory work has also fed into local educational and awareness-raising activities to raise awareness of local earth-built heritage and disseminate best practice in the renovation of earthen walls.