The name of this Austrian architect duo is a pun: Coop Himmelb(l)au – ‘Bau’ means building, ‘blau’ means blue, and ‘Himmel’ means either heaven or sky, so it’s either Blue Heaven Cooperative or Sky Building Cooperative. And the two architects build like rebels, skewing shapes and proportions, even in a building as symbolic as the new premises of the European Central Bank in Frankfurt.