Complex sentence: It encompasses two ethnic subneighborhoods, the largely Czech Karlin and the old Polish Warszawa, which on November 28,1980, was added to the National Register of Historic Places as Warszawa Neighborhood District.
Split into simpler sentences: It encompasses two ethnic subneighborhoods, the largely Czech Karlin and the old Polish Warszawa. On November 28,1980, Warszawa was added to the National Register of Historic Places as Warszawa Neighborhood District.