From Plarium Games Wiki
Buildings, Fortifications and hire Pirates to battle other captains. It is a secret hideaway from where players launch raids and blockades. Some Havens have 4 Gold Ores and 5 Stacks o' Lumber, others have 5 Gold Ores and 4 Stacks o' Lumber. The number of Gold and Lumber sources available in each Haven is varied in order to encourage Trading with other players at the Market. Exchange excess resources for ones you need - or sell them for additional Rum.