Empires III, the player advances through technological "Ages", representing historical time periods; these provide access to greater improvements, units, and buildings. They include the Discovery Age, which represents the discovery and exploration of the Americas by Europeans and allows the player to explore and develop their economy; the Colonial Age, which represents the European Expansion into the "New World" and unlocks early military units; the Fortress Age, which represents the fortification of the European colonies, unlocks forts, and allows the player to have a more complete military; the Industrial Age, which triggers a strong economy, due in part to factories—advanced buildings that automatically produce resources or artillery—and unlocks all units and shipments; and the Imperial Age, which unlocks all buildings and upgrades, and allows you to send unit and resource shipments a second time. All Ages cost food and coin to advance to, except the Colonial Age, which only costs food (800). The price of age advancement is incremental but does not vary between civilizations. Similar to the "minor gods" system in Age of Mythology, Age of Empires III uses a "Politician System" to grant bonuses on a successful advancement to another age. When the player chooses to advance to the next age, who is given the choice of two or more "Politicians" that provide them with a different bonus on choosing them. The Politician is given a generalized title from the period that usually reflects the bonus that it gives: for example, "The Naturalist" gives the player four cows, while "The General" gives twelve musketeers and one piece of heavy artillery. As the player's Home City increases in level, more Politicians are unlocked—at a rate of one for every ten Home City levels—up to level 60. Civilizations Age of Empires III allows the player to play as eight different civilizations: Spanish, British, French, Portuguese, Dutch, Russian, German, and Ottomans. Each of the eight civilizations has its own strengths and weaknesses and unique units available only to that civilization. Specific units for each civilization are designated Royal Guard units, receiving greater bonuses on the Guard upgrade in the Industrial Age, but at an increased price. The player can change the name of their Home City, the Explorer name, and is given a pre-named leader from part of the period (for example, Napoleon Bonaparte for the French Colonial Empire, Suleiman the Magnificent for Ottoman Empire, and Ivan the Terrible for the