The earthquake of December 23, 1972 in Managua, Nicaragua has led to what engineers are beginning to thick may be firm conclusions about earthquake resistant construction. In Managua there were two buildings located diagonally across the street from one another that were of nearly the same height but built from different design concepts. The difference between the two buildings was that one was a flexible frame with a light shear wall and the other contains heavy shear walls. The flexible frame of the 16 story plus two basement Banco Centrale did not undergo much damage but the interior of the building was a shambles. The 18 story Banco de America, however, which was built with shear walls, sustained negligible damage. Construction of both buildings has been completed at around the same time. It has been suggested that perhaps designers and code authorities ought now to stop asking if a structural design is the best choice for earthquake resistance and ask if the structural system is the best choice. Frames have seemed suitable in the past because they protected life and because they cut down on lateral load requirements. Yet their flexibility can permit great damage to the building itself. Shear wall buildings, on the other hand, reduce damage because they are basically stiffer. Furthermore, there is no premium cost for shear wall construction, but rather less cost. Shear wall buildings take advantage of the properties that are unique to concrete. If shear walls are tied into frame buildings the deflection of the combined system is much smaller than that of either system alone. Thus there are great opportunities for building very tall buildings with high resistance to lateral loads.