A kit for forming a wall comprises at least one building block having an exterior surface adapted to be closely stacked with a plurality of corresponding adjacent blocks and having at least one hollow in at least one surface thereof. A plurality of connecting ties each extending between first and second ends and having an enlarged portion located at at least one end thereof are utilized to connect and tie the building blocks together. The enlarged portions are adapted to be received within the hollows so as to span a pair of adjacent building blocks.