Complex sentence: The Helena Modrzejewska National Stary Theater in Kraków (Polish: "Narodowy Stary Teatr im. Heleny Modrzejewskiej"), firstly opened in 1781, is one of the oldest public stages in Poland and a national institution of culture.
Split into simpler sentences: The Helena Modrzejewska National Stary Theater in Kraków (Polish: "Narodowy Stary Teatr im. Heleny Modrzejewskiej"), first opened in 1781. It is one of the oldest public stages in Poland and a national institution of culture.