Complex sentence: In 1689 King Charles XI sold the mansion to his adviser Count Nils Gyldenstolpe, who rebuilt the mansion in "karolinerstil" (the typical style of the epoch of the two Swedish Charles kings), based of drawings by Jean de la Vallée.
Split into simpler sentences: In 1689 King Charles XI sold the mansion to his adviser Count Nils Gyldenstolpe. He rebuilt the mansion in "Swedish Carolean Style" ("karolinerstil"), the style of fashion in Sweden in the epoch of the two Carolean kings, based of drawings by Jean de la Vallée.