Thieves' guilds are constructed in woods. Thieves' guilds trains spies, which are an important and powerful unit in Lands & Lords.
Thieves' guilds with a high expansion level train spies cheaper, faster, and better (the trained spies have more experience) than guilds of low level. The sum of the expansion levels of all your guilds determines the maximum number of spies you can have at the same time (similar to castles and harbours). The research of the "Great Auditorium" additionally increases this limit.
Spies (from you or your allies) with low experience can be re-trained in guilds to reach the experience of newly trained spies coming from that guild. Spies in guilds also decrease their exhaustion faster than on other fields. For this, the research experience of the guild's owner is taken into account.
*The provided construction time does not take the research areas "Fatigue Duty" and "Industrial Cooperative" into account!
The cancellation of construction orders is possible at any time. 90 % of the paid ressources are returned.
Hints by experienced players
Every player should build a thieves' guild as soon as possible in one of the first acquired woods. This guild should get expanded to level X as fast as possible. All spies, even those trained in other guilds, should then rest there until their experience reaches 130 (this also requires the research of the "Secret Library"). This way, a player rapidly achieves a number of highly experienced spies. Smaller allies may also send their spies to this level X guild. You can never have too many spies, so don't be stingy about building guilds!