Karlsruhe is the second-largest city in the state of Baden-Württemberg, in southwest Germany, near the Franco-German border. It has a population of 296,033. Karlsruhe Palace was built in 1715 and the city is now the seat of two of the highest courts in Germany, the Federal Constitutional Court and the Federal Court of Justice.It has been speculated that Karlsruhe was a model for Washington, D.C. as both cities have a centre from which the streets radiate outward.GeographyThe city lies at an altitude between 100 m and 322 m . Its geographical coordinates are ; the 49th parallel runs through the city centre. Its course is marked by a stone and painted line in the Stadtgarten .The city was planned with the palace tower at the center and 32 streets radiating out from it like the spokes of a wheel, or the ribs of a folding fan, so that one nickname for Karlsruhe in German is the "fan city" . Almost all of these streets survived until today. 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.