Complex sentence: The Hôtel d'Alluye was owned for many years by the Robertet family before undergoing frequent changes in ownership; since 2007, it has been divided into ten apartments and a large office.
Split into simpler sentences: The Hôtel d'Alluye was initially owned for an extended period by the Robertet family but it subsequently underwent frequent changes in ownership. Since 2007, it has been divided into ten apartments and a large office.