Katowice is the largest city in Upper Silesia and Poland's main industrial centre. A rich cultural life with theatres, the Silesian Museum and Philharmonic Orchestras and the Spodek concert hall caters for a population of about 300,000 in the city and 2 million if the surrounding cities of the Upper-Silesian Metropolitan Union are taken into account. The Spodek concert hall is emblematic of the city, appearing in many postcards and other images.