anchor: You'll have to confine your viewing to the outside of the old citadel in the harbor, Fort Saint-Louis, unless you're able to obtain special visitor's permission from the French military (true of all Martinique's forts), or happen by during recently authorized but infrequent visiting hours. 
positive: The French military is in charge of Martinique's forts.
negative: Anyone can enter the old citadel of Fort Saint-Louis without permission.