Karlsruhe is a young, hospitable city, set in the Rhine valley between the hills of Pfalz and Vogesen, and the Black Forest, where you will immediately feel at home. 

Karlsruhe is known as the “fan city” (Fächerstadt).Because the founder of the city, Count Karl-Wilhelm, dreamed of a fan-shaped residence, and so the streets and the avenues meet like sun-rays in the center of the city – a baroque castle (Schloss) whose wings are aligning with the streets. With hundreds hectares of public parks and gardens, the city offers a diversity of green islands to relax that is pretty much unique in Germany.

The city is the home of the two highest federal courts of Germany: the Supreme Constitutional Court (Bundesverfassungsgericht) and the Court of Appeals (Bundesgerichtshof). 

More informations about  Karlsruhe you can find on one of these external links:

http://en.wikipedia.org/wiki/Karlsruhe

http://wikitravel.org/en/Karlsruhe

and if you are able to understand German, you can visit:

The CityWiki of Karlsruhe: http://ka.stadtwiki.net

The official site of the city: http://www.karlsruhe.de