Abstract: A set of toy building blocks has several different basic block shapes with multiple numbers of each shape. Each block has a magnetic base at one end that enables the block to be attached magnetically to the base end of another block. Further, each block has one-half of a mechanical connection at its other end that is complemental to certain of the connectors on other blocks in the set. The mechanical connectors at one end of the blocks and the magnetic couplings at the other, together with a variety of different shapes, preferably of abstract form, permit a wide variety of toy structures to be created and erected in accordance with the child's imagination and creativity.