THE INVENTION RELATES TO A BUILDING ELEMENT (18) DESIGNED TO CO-OPERATE IN SUPERPOSITION WITH AT LEAST ONE SIMILAR BUILDING ELEMENT, AND HAVING: A TOP FACE (1), A BOTTOM FACE (2), A FRONT FACE (3), AND A BACK FACE (4)； - AT LEAST TWO BACK VOIDS (5, 6) OF ELONGATE SECTION ALIGNED SUBSTANTIALLY PARALLEL TO THE BACK FACE (4) AND OPENING OUT IN THE TOP FACE (1) AND IN THE BOTTOM FACE (2)； - ON THE BOTTOM FACE (2), IN THE CENTRAL PORTION, A CENTRAL PROJECTION (7) SUITABLE FOR ENGAGING INTO ONE OF THE BACK VOIDS (5,6) OF A BUILDING ELEMENT (18) OF LOWER LEVEL； AND - ON THE BOTTOM FACE (2), A PROJECTING RIB (8) EXTENDING PARALLEL TO THE BACK FACE IN ALIGNMENT WITH THE INSIDE WALL (6A) OF ONE OF THE VOIDS (5, 6)； SAID BUILDING ELEMENT BEING CHARACTERIZED BY THE FACT THAT, ON ITS BOTTOM FACE, THE BUILDING ELEMENT IS PROVIDED WITH AT LEAST ONE DOG ADJOINING THE INSIDE WALL OF THE FRONT FACE OVER THE ENTIRE HEIGHT OF SAID INSIDE WALL. THE INVENTION ALSO RELATES TO BUILDING HALF-ELEMENTS AND TO A RETAINING WALL BUILT WITH BUILDING ELEMENTS AND WITH BUILDING HALF-ELEMENTS. THE INVENTION IS APPLICABLE TO BUILDING RETAINING WALLS REQUIRING BUILDING ELEMENTS THAT ARE EASY TO STORE, THAT ARE INTER-ENGAGABLE, AND THAT MAKE IT POSSIBLE TO BUILD ANY SHAPE OF RETAINING WALL. FIG. 1
