The passage grave of La Hougue Bie, in Jersey, has been known since 1924. Excavations are currently in progress on the cairn of this monument, which has not previously been explored. The 1991 and 1992 excavation seasons have revealed the existence of two concentric walls, which seem to belong to two separate phases of Neolithic construction. The primary cairn had a diameter of 35 mètres, with a single wall, 9 mètres high. This cairn was later enlarged by the construction of an earth terrace, with a second wall, 47 mètres in diameter.