Abstract: An improved building block (12) for constructing an exterior wall (14) comprising a solid body (16) having a front face (18), a rear face (20), two end faces (22), a top face (24) and a bottom face (26). A plurality of alignment projections (28) are on the top face (24) of the solid body (16). The bottom face (26) of the solid body (16) has a plurality of alignment sockets (30) therein. When a plurality of the solid bodies (16) are laid side by side and are stacked offset one upon the other to make a plurality of courses (32), the alignment projections (28) will engage with the alignment sockets (30) to form equally spaced joints (34) therebetween to be filled in later with mortar (36), to construct the exterior wall (14).