Abstract: A building block for construction of a structure, such as house, is provided that is lightweight and portable. The building block has a first or lightweight portion that can be made from a thermally insulative material. The building block also has a second or rigid portion that can be made from a material having a high compressive strength. The first and second portions are affixed to each other to provide a preformed building block with a high compressive strength. The rigid portion can be a number of rigid sheets substantially embedded in the lightweight portion.