Complex sentence: In addition, the duc de Penthièvre was the only heir of his father, the comte de Toulouse, from whom he inherited the Hôtel de Toulouse in Paris, and the Château de Rambouillet.
Split into simpler sentences: In addition, the duc de Penthièvre was the only heir of his father, the comte de Toulouse. From him, he inherited the Hôtel de Toulouse and the Château de Rambouillet.