I assume you know that Key Tower was derived from the original design for the Wells Fargo Tower in Minneapolis. Cesar Pelli designed a 950-foot tower (see the image below) on the site of the burned-out HQ of Norwest Bank in downtown Minneapolis.
But Norwest eventually changed the program and so Pelli designed a new Neo-Deco tower for Minneapolis. However, he adapted the original design for Cleveland and it became Key Tower.
Beautiful work in both towers!
Pelli's Norwest Tower in Minneapolis:
Pelli's Wells Fargo Tower in Minneapolis: