The assignment was to create 4-8 thumbnail sketches of a moment in time from our personal history. I used to work in NYC and I remember looking down across the city on a particularly foggy day and seeing the skyscrapers vanish into the fog below. I added in the idea of placing the concept art in a near future story where perhaps the ground was dangerous or heavily polluted, and so people walked between skyscrapers on long elevated footbridges or sidewalk.