The Heart of Rome

Historical novel set in 18thC Rome. The family of the heroine is suddenly impoverished her selfish mother leaves her with a social-climbing woman who's married to Baron Volterra the man mainly responsible for the fall of the Conti family. An architect (Malipieri) moves into the the Conti palace to search for lost treasure. When he falls in love with Sabina, the young heroine, she goes with him to see the treasure and they are trapped by "lost water". She spends the night in his room and her reputation is ruined. He married when young to save the reputation of the lover of his dead friend and has never lived with his wife, who saves the day when she comes to Rome and suggests that they go to Switzerland to get a divorce.