You know you're old when the once-modern building where you landed your first job has been designated an historical site. On Monday, July 5th, 1965 I walked into the shiny marble lobby of the Maclean-Hunter Building at 481 University Avenue in Toronto to begin my first full-time job. Bell Canada leased space in the building and they'd hired me to start work as a clerk-typist, beginning the week after I finished high school. I was 17 years old and wore a pink and white gingham dress and new white high…