From Arcanum Illyria
Illyriad is full of undocumented features and locations that offer special bonuses or benefits. These Mysteries are left up to the player to discover by exploring the world and Illyriad's lore (or reading up here). Solutions to mysteries often involve the use of diplomats to visit various features on the map and hints from Faction information or articles from The Illyriad Herald. The benefits may be restricted to low-population cities, new cities, old cities, or only work once per city, but the benefits themselves are often quite significant, and worth searching out.