The Seattle world's fair is a vast showcase of varied uses of concrete. If it is a glimpse into century 21, the concrete industry can look forward confidently to a remarkable increase in volume. The two shell roofed buildings fascinate all fair visitors with their beauty. Concrete men are interested because they offer proof that unusual concrete techniques can cut construction costs rather than increase them as many people believe. The economy of these structures was achieved because the 52 shells were cast with only two pairs of column forms and three pairs of shell forms. It took two weeks to set up the first shell but the repetition of the process made the crew so skilled in the technique that they soon were forming on shell per day.