Leslie E Robertson was the lead structural engineer of the World Trade Center complex, and is seen here standing proudly at the foot of the pinnacle of his career.

The World Trade Center project was a big moment in Leslie's career, at just 34 years old he was tasked with the monumental challenge of bringing the world's tallest, most complex buildings to reality.

Instagram Photo Credit: twinsofnyc911

Born in 1928, Robertson has since been structural engineer on numerous other projects, including the Shanghai World Financial Center and the Bank of China Tower in Hong Kong. His engineering career began in 1952, when he joined Kaiser Engineering. In 1958 he joined the Seattle structural and civil engineering firm Worthington and Skilling. Robertson was selected by Worthington, Skilling, Helle, and Jackson (WSHJ) to participate in the design of the World Trade Center Twin Towers between the years 1966 and 1971, his first high rise construction. In 1967, Robertson was made a partner and WSHJ was renamed Skilling, Helle, Christiansen, Robertson. The firm split its operations in 1982, with Robertson renaming the East Coast office Leslie E. Robertson Associates RLLP.

Since the collapse of the World Trade Center in 2001, debates about the safety of rent-space-maximized designs have engaged the profession, but most would agree that the design of the World Trade Center actually withstood the impact of the plane with enough time to allow many thousands of occupants to evacuate safely. Robertson's firm later participated in the development of a database of basic structural information for the towers of the World Trade Center (WTC1 and 2) for NIST and FEMA, and to record the undocumented structural changes that had been made to the buildings after construction began.