I saw this amazing set of mosaics on a 1970's East German office block in Potsdam recently. It's called 'Man conquers Space' (Der Mensch bezwingt den Kosmos) by artist Fritz Eisel. You really can't get much more Socialist than that.
The below panels were installed incorrectly, the one on the right should have been on the left and the one on the left all the way on the right, it also needed to be rotated by 180degrees. Pretty sure someone would have got into serious trouble for that!!