Abstract: Building blocks for use as toys which have six identical faces and interlock by 1, 2 or 4 quarters of each face, On each of the six faces of the building block there are provided four quartered sections, two of which are projecting with respect to the broadest plane of the face and two of which are recessed with respect to the same plane. Each of the projecting quarters of each face have a hole of a predetermined dimension in the center thereof; and each of the recessed quarters have a peg extending therefrom. The blocks may be connected as above mentioned by either 1, 2 or 4 quarters of each face with the complementary quarters of a second block. An unlimited number of blocks may be connected to form complete structures as desired.