Mes is the Stronghold that separates the North from the South (in the Northern Human States). It has a very strong military tradition, and it trains high level generals from all around the world.
Its high white walls have never been breached, even though they hold no secrets. They are a tourist attraction and the pride and glory of this city state.
In the past Mes has been hired to build fortresses in other lands, but their prices kept getting higher. Now they are 1000 times the normal high quality building prices for non-Messians.