Complex sentence: Once completed, the castle boasted 30 rooms, including a ballroom; outbuildings and other improvements included a water tower, a lagoon for his steam yachts, a guesthouse, a boathouse and an ice house.
Split into simpler sentences: Once completed, the castle boasted 30 rooms, including a ballroom. Outbuildings and other improvements included a water tower, a lagoon for his steam yachts, a guesthouse, a boathouse and an ice house.