The Tunnel of the Founders is a series of tunnels under the dwarven town of Vergen. Spoiler warning: Significant plot details follow. Roche's path: Geralt must search these tunnels in order to meet up with Zoltan and Saskia in order to get the Commander's sword; and later Geralt and Vernon use the tunnel to enter Vergen after the Blue Stripes are viciously murdered by the Kaedwenis. Significant plot details end here.