One would have to have a very discriminating eye to notice it, but they were actually designed by five different architechture firms and I'm sure the slight difference in curtain wall appearance was considered mindblowingly radical in Sweden during the 50's and 60's. The worst sin however is that the architechtural zeitgeist dictated that "good architecture" equaled "fast to build", which is why they have an outer shell of white... something... that due to dirt far too often looks like a toilet that needs a once-over with the brush. The cloud does have a silver lining, though: They were completed right before the hippie era rolled in and were thus not painted orange, brown and/or green.
On 1 November 2007 the installation Emotional Cities[b] was activated. It consisted of a set of colored lights that would light up the facades of the Haymarket buildings in a color determined by how people felt. The measurement of the citizens' feelings was done via a website where one could log in and click on a scale from purple (sad) to red (happy). The installation ended on 6 January 2008, but the lights remained and are now used to light up the otherwise dreary facades at night.