Abstract: A toy building block having on one face thereof at least one row of mechanical coupling pins and opposite thereto mechanical counter-coupling tubes for coupling said toy building block to a similar toy building block either with the row of said coupling pins parallel to a corresponding row of coupling pins of said similar block or perpendicular to said corresponding row. The toy building block includes first and second current paths connected to first and second contact areas respectively designed to establish electrical connection with first and second contact areas in a similar block. The first and second contact areas are disposed in first and second angular sectors about adjacent coupling pins. The angular sectors are offset from each other and do not overlap regardless of whether the building block row of coupling pins is parallel or perpendicular to the row of coupling pins of the similar block.