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 town 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. The city lies at an altitude between 100 m (on the eastern shore of the river Rhine) and 322 m (near the communications tower In the suburb of Wettersbach). Its geographical coordinates are 49°00'N 8°24'E; the 49th parallel runs through the city centre. Its course is marked by a stone and painted line in the Stadtgarten ("city park").

The city was planned with the palace tower (Schloss) 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" (Fächerstadt). 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.

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).

The market square lies on the street running south from the palace to Ettlingen. The market square has the town hall (Rathaus) to the west, the main Lutheran church (Evangelische Stadtkirche) to the east, and the tomb of Margrave Karl Wilhelm in a pyramid in the buildings, resulting in Karlsruhe being one of only three large cities in Germany where buildings are laid out in the Neoclassical style.

The area north of the palace is a park and forest. Originally the area to the east of the palace consisted of gardens and forests, some of which remain, but the Institute of Technology (founded in 1825), Wildparkstadion, and residential areas have been built there. The area west of the palace is now mostly residential.