What is... ?
Agricultural Industrial Military
Field Drainage
Irrigation
High Yield Grain
Fertilizer
Ploughs
Steam Tractors
Insecticide
Cross Pollenation
Veterinary Care
Animal Husbandry
 Public Sewage
Border Crossing Guards
Basic Plumbing
Blacksmiths
Lumbermills
Multi-Unit Housing
Basic Mining
Gunpowder
Steam Engines
Churches
Organized Cities
Printing Presses
Libraries
Schools
Hospitals
Research Centers
Fire Brigades
 Camoflauge
Siege Towers
Catapults
Tiger Pits
Steel Armor
Advanced Subterfuge
Iron Armor
Mithrill Armor
Hand Cannons
Cannons
Matchlock Muskets
Field Hospitals
Flintlock Muskets
Rifled Muskets
Mk 4 Turbo Meson Cannons
Longbows
Crossbows
Steel Bolted Crossbows
Reinforced Stone Barricades
Burning Pitch Catapults
Peripheral Moat
Burning Pitch Moat
Petards
Hand Grenades
Trebuchets
Proving Grounds