Photographer David Harpe captured this video of fog consuming the city of Chicago at night earlier this week and it was shared via WGN TV. I think this clip has to have been taken from the Sears Tower (and I will not call it anything else).
21,000 years ago, the ice over Montreal was 3 kilometers thick, and dwarfed the Sears and CN Towers. The land is still rising back up like a sponge from the great weight of the ice. Conditions changing over time. (xkcd)