Charles Dickens had several reasons for writing "A Tale of Two Cities." One reason, and the basic reason any author publishes a novel is to earn money. Dickens had this novel published in a serial format with a few chapters being released each month. The people would get hooked on the story and continue to buy the publication each month so they could see what happened next in the story.
Another reason Dickens wrote this novel was to try something different. He had always written about the Victorian era but with this book he was delving into a new area. This novel would be a romantic novel set in the time of the French Revolution. The two cities being Paris and London. Dickens was not very kind to either city and part of his story spends considerable time discussing the unfairness of the Feudal system and how badly the King treated his subjects.
Most people who have read this book either love it or really hate it. The critics during this era could not agree as to whether or not this experiment in writing was sucessful or not.