21	Intricate brick vaulting in Iran. The three dimensional roof vault loads are resolved into point loads resited by stone columns.
no 22	Preditermined failure modes of banana stems. Failure, as in trees is a creative event in nature!
no 23	Calatrava's sculptures may be turned into a real 50 tory building in New  York. Other experiments along the same lines by kids moving pop cans and bottles!
no 24	Thin shell hypoerbolic paraboloid surface structures by Felix Candela. Very efficient in material cost but costly in labour cost.
no 25	The 52 story Cartagena tower that was  permanently bent out of shape by a windstorm.This Vierendeel structure was not rigid  enough and was doomed to failure. to the sixth-five