Kalypso Media has just announced the release of DLC for the Windows PC version of Port Royale 3 (console versions of the content are to be released at a later date). The DLC offers new buildings and decorative objects, as well as some additional gameplay tweaks.
Here's the details from Kalypso and some new screens:
"Six new buildings (including embassy, fire department and more).
Decorative objects such as plants, statues and various types of street coverings.
More control over city defensive lines.
An economic adviser to assist players in making financial choices.
The ability to build your own ships."