Now, time to recheck those flanks...... Parts of this page have been identified as no longer being up to date with recently released material.
The Tavern is a building which sets the maximum possible number of spies you can have. Taverns are required for an espionage. Taverns can only be built at the main castle in The Great Empire, and the maximum number of buildings is 3, making the maximum possible agent number 39, or 44 with research. The number of agents can be further expanded in the research tower. The more city guards the NPC or castle lord you are spying at has, the more you will get caught by the target, and alerting the target that you are spying on them.