The Staatstheater Cottbus holds a distinction unique in Germany: it is the only theatre building in the country constructed in the Jugendstil (Art Nouveau) style. Built in 1908 and beautifully maintained, the building on Schillerplatz just west of the Altmarkt is worth seeing even if you are not attending a performance.
The theatre's reputation extends well beyond Cottbus — it produces opera, ballet, drama, and concerts at a standard unusual for a city of this size, attracting audiences from Berlin and Dresden. Tickets are much less expensive than comparable Berlin productions. If you are in the region and a performance is on, it is worth attending for the building alone.