As an architect and builder in the Chicago-area, I am familiar with the Monadnock Building in Chicago, which has both an iron frame and a load-bearing exterior masonry wall (more than six feet at the base).
I worked on an elevator retrofit project in downtown Chicago in the Nineties. There are so many safety features in the system that I felt comfortable sitting on top of each elevator and riding during numerous tests, including sudden stops and stop and go action.
The programming involved in the design of the elevator system is phenomenal. The system can be tweaked to shorten or lengthen stops and recognize other cars in the system and thereby become express cars if a certain number are stopped on a particular floor.
Very interesting, thanks. I recall the Monadnock being architecturally seminal and visited it on lunch hours downtown.