Complex sentence: San Francisco was a port of entry for the family many times and she lived for awhile in a huge white-pillared mansion on the side of a hill that became the Sugar Hill Hall mansion which served as the setting for some of her most popular books.
Split into simpler sentences: San Francisco was a port of entry for the family many times. The huge white-pillared mansion on the side of a hill that she lived in became the Sugar Hill Hall mansion which served as the setting for some of her most popular books.