In reply to icehockeyhair:
There are only two dedicated bouldering walls, both run by the same company so with much the same setting style & atmosphere. Boulderwelt Ost is in the city centre; Boulderwelt West is a bit out of town so (slightly) less overcrowded on weekday evenings.
Of the routes-and-bouldering walls, the DAV one at Freimann (north, near the stadium) has by far the biggest & best bouldering area.
Post edited at 18:43