Groundbreaking had taken place seven years earlier, but construction of Towers 1 and 2 was delayed until 1968 and 1969 respectively while the site was excavated and a wall was constructed to prevent water intrusion from the nearby Hudson River. The towers had topped out and tenants had begun moving in, but April 4th marked the ribbon-cutting ceremony that officially opened the towers. Construction required razing 13 square blocks of Lower Manhattan that included a section of electronics retailers known as Radio Row. The towers would remain the world's tallest until the completion of the Sears Tower in Chicago just one year later, and would remain standing 28 years until the September 11th attacks. ☮️