On August 7, 1974, two years after the second World Trade Center tower was opened, French daredevil Philippe Petit walked along a wire strung between the two buildings. Construction on the WTC towers began in 1966. The north tower was completed in December, 1970, and the south tower in January, 1972. To make way for the Center’s 16-acre site, five streets in lower Manhattan were closed and 164 buildings were razed. During peak construction periods, 3,500 people worked at the site; in total, the construction employed 10,000 workers. Sixty died on the job.