Teatr Polski is one of Bielsko-Biała's main cultural anchors, a late-19th-century theatre that fits the city's old Habsburg polish. Even if you do not understand Polish, the building is worth noticing for its confident facade and traditional auditorium.
The real reason to go is a performance, so check the programme before treating it as a sightseeing stop. It pairs well with a walk through the old town, where Bielsko-Biała's theatre, villas, and commercial buildings show why the city is often more elegant than first-time visitors expect.