Complex sentence: For two decades, Hyde Park House served as a focal point of Hyde Park social life, and was visited or lived in by many prominent guests, including Mary Todd Lincoln, who lived there for two and a half months in the summer of 1865.
Split into simpler sentences: For two decades, Hyde Park House served as a focal point of Hyde Park social life. During this period, it was visited or lived in by many prominent guests, including Mary Todd Lincoln, who lived there for two and a half months in the summer of 1865.