Our second-tallest building opened in 1983 as One Mellon Center. It was actually meant to be the Dravo Building, but Dravo disappeared before the building was finished. There were plans to surround it with matching smaller buildings, but the 1980s boom went bust, and those buildings never happened.
The architects were Welton Becket and Associates—clearly the Associates in this case, since Mr. Becket himself died in 1969. (He is, however, credited with this and nearly three dozen other posthumous buildings in his Wikipedia article.)