Abstract: The invention is a modular-shaped, lightweight concrete block that can be pivotally interlocked with other blocks of the same size without having to use grout and pins or additional attachment apparatus. The building block comprises a pair of vertically aligned side faces and horizontally aligned top and bottom faces that are joined at opposite lateral ends with rounded end faces. A pair of tenons extend out the top face of the block at opposite lateral ends and are coaxially aligned with complementary mortises formed into the bottom face. The unique end face configuration in combination with the location of the tenon, allow two adjacent blocks to be interlocked together in a wide range of angles. The invention also includes a novel handle configuration that is located in the middle of the block.