In big cities, you often see advertising on the sides of buildings. This typically takes the form of static billboards, although giant LED displays and projected images are making inroads too. But what about buildings that are under construction? Aside from a few signs promoting the financing company, even the high profile buildings here in Chicago are devoid of advertising. Just think of all the clever campaigns that somebody could run on the empty canvas of a skyscraper during its multi-year construction phase. Unless there’s some ordinance that prevents using unfinished buildings like this, it seems like a logical way to generate revenue before a new building opens its doors.