Monaco is a sovereign city-state, and country, located at Western Europe. One of the smallest European countries to date, Monaco is primarily bordered by France and the Mediterranean Sea. While the country doesn't have impact on modern fiction, it is still mentioned in several works. Particularly, the animated film, Freddie as F.R.O.7., depicts the country as one of the main locations of the film.
That said, Monaco is also mentioned in the early events of Heroes vs. Villains War, displayed by the appearance of Prince Frederic's castle, originated from the said animated film, as well as the hero's nationality. Other than that, Monaco does not make another appearance, nor mentioned by its various characters.