 Because of this city layout, in metric geometry, Karlsruhe metric refers to a measure of distance that assumes travel is only possible along radial streets and along circular avenues around the centre.The city centre is the oldest part of town and lies south of the palace in the quadrant defined by nine of the radial streets.The central part of the palace runs east-west, with two wings, each at a 45° angle, directed southeast and southwest (i.e., parallel with the streets marking the boundaries of the quadrant defining the city center).