Sparta is history, and is not owned by any company--other than any original art such a company may have produced or any thing they may have trademarked or copyrighted, like the name of their movie, for example. You are just as free as they were to create your own art/concept based on this ancient history.
Though I'm sure someone will try to tell you otherwise out of an overabundance of fear of the legal profession.
Though I'm sure someone will try to tell you otherwise out of an overabundance of fear of the legal profession.