Toy building blocks

A box comprising an integral monolithic paperboard blank, folded to form a toy building block comprising:

• first and second sidewalls comprising a first pair of opposed sidewalls, third and fourth sidewalls comprising a second pair of opposed sidewalls, the first and the second pair of opposed sidewalls cooperating to form a double-ended hollow tube;
• a pair of opposed end walls at the ends of the tube and cooperating therewith to enclose an interior volume;
• a plurality of tabs extending from the first sidewall and spaced apart in a preselected pattern, the second sidewall located opposite the first sidewall and defining a corresponding plurality of spaced apart primary apertures, arranged with the same pattern as that of the tabs;
• the third and the fourth sidewalls defining a plurality of secondary apertures cooperating with the primary apertures to form a continuous opening for receiving the tabs of another paperboard box;
• and
• two spaced-apart pairs of spaced-apart interior walls, carrying the tabs, the third and the fourth sidewalls completely overlying the first pair of opposed interior walls.