when was the twin towers built

The Twin Towers of the original World Trade Center in New York City were constructed primarily between 1966 and 1973. Construction officially began with groundbreaking in August 1966. The slurry wall foundation work started early in 1967, and excavation continued through 1968. The North Tower (1 World Trade Center) construction began in August 1968, topped out in December 1970, and the South Tower (2 World Trade Center) started in January 1969, topping out in July 1971. The towers were officially completed and ceremonially opened on April 4, 1973.