Complex sentence: By 1896, Mrs. Ava Astor had become socially active in England with a country estate, Sutton Place in Guildford, Surrey, and a townhouse at Grosvenor Square in Mayfair, London.
Split into simpler sentences: By 1896, Mrs. Ava Astor had become socially active in England. She had a country estate, Sutton Place in Guildford, Surrey, and a townhouse on Grosvenor Square in Mayfair, London.