Optional Techs in C3C:
Ancient Times:
Literature- Allows construction of Libraries and the Great Library Great Wonder
Monarchy- Allows Monarchy Government
The Republic- Allows Republic Government
Middle Ages:
Chivalry- Allows Construction of Knights (4/3/2) and Knights' Templar Great Wonder
Music Theory- Allows construction of the JS Bachs' Cathedral Great Wonder
Printing Press- Allows trading of Communications with other civs
Democracy- Allows Democracy Government
Free Artistry- Allows construction of the Shakespeare's Theater Great Wonder
Economics- Allows construction of the Smith's Trading Post Great Wonder
Navigation- Allows trading of Territory and World Maps with other civs
Military Tradition- Allows construction of Cavalry (6/3/3) and the Military Academy Small Wonder
Industrial Ages:
Nationalism- Allows
Mobilization of your economy and construction of Riflemen (4/6/1)
Communism- Allows Communism Government
Fascism- Allows Fascism Government
Espionage- Allows construction of Intelligence Agency and (in Communism) Secret Police HQ
Ironclads- Allows construction of Ironclads (4/4/4)
Sanitation- Allows construction of Hospitals
Amphibious War- Allows construction of Marines (12/6/1/Amphibious Assault)
Advanced Flight- Allows construction of Helicopters (0/2/Range of 4), Paratroopers (4/9/1/Range of 6), and Radar Tower worker improvement
Modern Times:
NONE