Complex sentence: The reasons for building the Palace were to have a new magnificent administrative capital of the Kingdom in Caserta and to preserve the court by possible attacks from the sea; as well the King decided to build a theatre, a large library, and a university.
Split into simpler sentences: The reasons for building the Palace were to have a new magnificent administrative capital of the Kingdom in Caserta and to protect the court from possible attacks from the sea. The King also decided to build a theatre, a large library, and a university.