Construction work began on the North Tower in August 1968 with construction beginning on the South Tower by January 1969.[135] In January 1967, $74 million in contracts were awarded to the Pacific Car and Foundry Company, Laclede Steel Company, Granite City Steel Company, and Karl Koch Erecting Company to supply steel for the project.[136] The Port Authority chose to use many different steel suppliers, bidding on smaller portions of steel, rather than buy larger amounts from a single source such as Bethlehem Steel or U.S. Steel as a cost-saving measure.[137] Karl Koch was also hired to do all the work of erecting the steel, and a contract for work on the aluminum facade was awarded to the Aluminum Company of America.[136] Tishman Realty & Construction was hired in February 1967 to oversee construction of the project.[138]
thanks re: the steel...