A system and method for constructing and using modular building blocks. The blocks may include two walls, a course, end conditions, a reinforcing assembly, and vertical and lateral retaining members. The walls may include lateral supports disposed lengthwise on a top and a bottom surface. Lateral retainer members may be disposed into the lateral supports. The walls may also include channels extending from the top surface to the bottom surface. Vertical retainer members may be disposed into the channels. The course may be disposed between and coupled to the walls and characterized by one or more turns. The reinforcing assembly may be set inside the walls and the course. The reinforcing assembly may include wire mesh portions disposed to form interlocks, where the interlocks provide structural support for the channels. The modular building blocks may be coupled together with structurally complimentary end conditions.