Rise of Nations features eight detailed ages for your nation to advance through. To progress through the ages, you must research technologies in four different fields at your library:

• Military: Increases population limit and allows new military units and upgrades
• Civic: Increases maximum number of cities and expands national borders
• Commerce: Increases commerce limit and maximum number of caravans
• Science: Decreases cost & time of other research, and increases some units' line-of-sight

Ancient Age

The Art of War - Barracks, Stables, and Towers may be constructed. City State - Allegiance and Taxation upgrades. Barter - Docks and Markets may be constructed. Written Word - Temples may be constructed. Units can cross seas.

Classical Age

Mercenaries - Siege Factories and Forts may be constructed. Empire - Religion upgrade. Coinage - May buy/sell resources at market. May colonize other continents. Mathematics - Granaries and Lumber Mills may be constructed. Herbal Lore and Construction upgrades.

Medieval Age

Standing Army - Tactics and Fortification upgrades. Feudalism - Oath of Fealty and Vassalage upgrades. Trade - Your caravans may trade with peaceful nations' cities. Chemistry - Smelters may be constructed. Medicine, Agriculture, Architecture, Carpentry, Forage, and Literacy upgrades.

Gunpowder Age

Conscription - Operations and Bombardment upgrades. Divine Right - Monotheism upgrade. Mercantilism - General commerce benefits. Laws of Nature - Crop Rotation, Logging Industry, Printing Press, and Metal Alloys upgrades.

Enlightenment Age

Levee en Masse - General military benefits. Constitution - Patriotism and Social Contract upgrades. Finance - General commerce benefits. Electricity - Pharmaceuticals, Engineering, Scientific Method, Supply, and Cold Casting upgrades.

Industrial Age

Nation-in-Arms - Strategy and Strategic Reserve upgrades. Great Power - Existentialism and Income Tax upgrades. Assembly Line - General commerce benefits. Electronics - Refineries may be constructed. Food Industry, Papermill, Steel, and Institutional Research upgrades. Entire map becomes explored.

Modern Age

Selective Service - General military benefits. International Law - Nationalism upgrade Globalization - General commerce benefits. Computerization - Logistics and Supercomputer upgrades. All buildings and units in your territory revealed.

Information Age

Missile Shield - Enemy missiles cannot target you. Armageddon Clock turned back by 2. World Government - All victory timers and assimilations are instantaneous. Global Prosperity - Resource gathering bonus. Commerce and population limits to maximum. Artificial Intelligence - Units produced instantly.