How about researching some aspect of Dicken's novel about the French Revolution, A Tale of Two Cities? For instance, what part did characters like Madame Defarge play in the revolution?
This may be more commonplace, but the actual storming of the Bastille would make an interesting research topic.
Hmm I was thinking something to do with the Bastille but I can't actually say, "how did the bastille effect the French Revolution" can I? I guess it would have to be more specific than the actual building.
And i'm not sure that a book would work with history?
Since Dickens' novel is about the French Revolution, you could use it as a "jumping off point" for your essay. You could research the part that ordinary people, like Madame Defarge, played in the Revolution.
The Bastille was a symbol of the revolution and France's national independence day, July 14, is called Bastille Day. Why did it become a symbol, when the actual event was almost a non-event?