An impact-resistant wall structure is fabricated from two types of sheet metal cellular panel units and concrete columns which are enclosed thereby. Inner sheet metal cellular panel units are secured to outboard members of a building framework. Outer sheet metal cellular panel units are secured outboard to the inner sheet metal cellular units with the cells of the inner units perpendicular to the cells of the outer units. The inner sheet metal cellular units cooperate with the outer sheet metal cellular units to provide total peripheral metal enclosure for concrete columns. The outer sheet metal cellular units are fastened to the inner sheet metal cellular units at contiguous points preferably by means of threaded fasteners which extend into the concrete columns. Reinforcing rods positioned within the cells of certain or all of the panel units provide increased tension reinforcement, increased shear resistance, and produce local damage to impacting missiles. A decorative sheathing may be applied outboard of the outer sheet metal cellular units, if desired.