Spies is a technology in Age of Empires III, available in the Imperial Age. It costs 75 coin per enemy unit, and lets the player see everything that their enemies see.
It can be researched from the Capitol for European civilizations, and from the Town Center for Asians and Native Americans.
| Capitol technologies | |
|---|---|
| Blockade · Spies · Knighthood · Peerage · Legendary Native Warriors · Immigrants · Large Scale Agriculture · Deforestation · Excessive Taxation · Cadets · Brigadier General | |
| State Capitol technologies | |
 | Oregon Trail · State Constitutions · Statehood |
 | Cadets · New Mexico Immigration |
 | Blockade · Spies · Brigadier General · Legendary Native Warriors · Iowa Farmlands · Pine Tree State · Mountain State Gold Rush |
| Other civilization's counterparts | |
| African | Large Scale Farming · Ebony Exports · Strangers' Quarters |
| Asian | Mechanized Rice Cultivation · Tropical Timber Trade · Collective Economy · Exalted Natives |
| Native American | Large Scale Gathering · Deforestation · Excessive Tribute · Legendary Native Warriors |