Complex sentence: She sang for both Sigismund III Vasa and for Władysław IV Waza on his visit to Danzig, then to the imperial city of Milan and a year-long visit to a number of other European cultural cities.
Split into simpler sentences: She sang for both Sigismund III Vasa and for Władysław IV Waza on teh occasion of their visits to Danzig. She went to the imperial city of Milan and on a year-long trip to a number of other European cultural cities.