Abstract: A hollow building wall including two wall components comprised of vertical arrays of stacked, integrally formed, hollow building blocks, which arrays are connected by vertically oriented, rigid separator splines that extend continuously from top to bottom of the wall at frequent horizontal intervals along the wall, to securely engage and support the two vertical arrays of building blocks. Each edge of an individual spline is secured in one of a plurality of vertical grooves on the inner surfaces of each wall component. Each building block is attached positively at each end to one or more horizontally adjacent building blocks. The positive attachment of horizontally adjacent building blocks and the separator splines forms in effect a structural "tube" that extends from top to bottom of the wall and is connected positively with other similar "tubes" disposed along the length of the wall.