An official expansion to Age of empires III, Glenn Drover's Empires: The Age of Discovery, the Builder Expansion contains:
1) A NEW SPECIALIST: THE BUILDER
2) 20 NEW CAPITAL BUILDINGS
3) A RULES SHEET with the new Builder Rules, Capital Buildings, and even special rules for a historical start (Each Nation has a special ability and one or two Capital Buildings to start the game). The idea is that the Spanish will feel like the Spanish (Conquistadors, etc.), The English will feel like the English, the Dutch like the Dutch, etc.
4) All the miniatures to add the six player 8 purple color).