Well that's a shame, since Cordoba in España lost its Communist mayor last year, that would have probably be the largest European city with a Communist mayor !
Anyway that's pretty comforting to see that voters are still capable sometimes of switching away of a centre-left party that compromises too much with the right to go for a more left-wing party not willing to do so. SPÖ must ask themselves questions now...
Oh and another thing : those councils with even numbers of seats are just ridiculous. You just don't do that.
Since the lost of Cordoba, I think that the most important city with an IU mayor is Rivas-Vaciamadrid (pop. around 73000), in the Spain's capital periphery. That town is called the Gaul village of the left in Madrid and its mayor, José Masa, has developed some advanced social and environmental policies. In Catalonia ICV retains El Prat de Llobregat (pop. 63500), although many IU militants regard the ecosocialist party as a vile bunch of socialdemocratic revisionists. I think that in Andalusia IU doesn't control any municipality above 50000, but I might be wrong.