A mortar-less building block system including interlocking building blocks, joist hangers, truss brackets, and insulation member disposed exterior to the block; the block having a front face and a back face, a top face and a bottom face, and a protrusion side face and a recess side face all connected to form the building block; the front face and the back face each have a pair of longitudinal recesses aligned with the longitudinal recesses of the front face and the back face, and the top face further having a transverse recess centrally located on the top face transversely intersecting the pair of longitudinal recesses, creating intersection points; the recess side face having a transverse recess aligned with the transverse recess of the top face, and the protrusion side face having a transverse protrusion designed to mate with the transverse recess of an other of the building block; the bottom face having at least one transverse protrusion for mating with the recess of a top face of an other of the building block, the transverse protrusion aligned with the recess of the recess side face, and aligned with the protrusion of the protrusion side face; the mortar-less building block having a pair of bores allowing a user to place a rod within the bore to lock multiple blocks together.