In Marsal, near Nancy (Moselle), are the remains of Iron Age sites (7^th to 1^st century BCE) for the production of salt. They made use of natural salt sources and are known as the “Briquetage de la Seille” (Seille brickwork). Field work is carried out by participants on an international professional training scheme, led by a team of professional researchers and doctoral students. The site shown here, the Digue, was used by salt workers in the 6^th century BCE. The aim of this study is to understand the organisation of Celtic salt workers and identify the techniques used for salt production in the Iron Age.