Catan - Expansion Cities & Knights

In Catan: Cities & Knights you engage in the defense of Catan and compete to build the three great metropolises of Catan. Each of these magnificent urban centers is even more valuable than a city. They're also immune to the dangerous barbarians. Invest in city improvements, which you acquire using three commodities of trade: coin, paper, and cloth. If you improve your culture, muster your knights, and enrich your fine cities, you will be the master of the great realm of Catan!