Kaiser Cross Highway is a road that runs along the axis of quadrants, as denoted by a sign in the center of this road before -2k-2k. Confirmed part starts at a water cube around -1500, -1500 and stretches in the direction to Imperator's Base (ruins of which are scattered around -1M) and is excepted to reach the World Corner in it's Nether version. At least if players don't take the Swastika center-to-border-to-corner approach.