Karlsruhe is located in the Rhine valley, where the French-German border makes that sharp twist from north-south to east-west. Karlsruhe is sometimes referred to as the 'Gateway to the Black Forest', although this term is more correctly applied to the city of Pforzheim. Karlsruhe lies at the north western-edge of this beautiful wooded mountain range.
There are a few possibilities to get to Karlsruhe. First and least recommended is travelling by car. You can reach Karlsruhe via the A5 from Frankfurt or Basel, or via the A8 from Stuttgart (for more information on German freeways see Driving on Autobahns in Germany). Another way of travelling to Karlsruhe is by air. There are four airports in the vicinity of Karlsruhe: Frankfurt, Stuttgart, Strasbourg (France) and last, but not least, the Baden Airpark near Baden-Baden. From each of these, you have to travel by car or train for up to an additional hour. The recommended way of getting to Karlsruhe is travelling by train from almost anywhere.
Why is this method recommended? Because Karlsruhe has a great system for public transport; the Straßenbahn. This is a system of electric trains, which cross the city and many of the surrounding smaller towns. Every inhabitant of Karlsruhe has a stop for the Straßenbahn or the bus within 250 metres of his home. There's absolutely no need for a car in Karlsruhe.
The primary nickname of Karlsruhe is 'Residence of Justice' as the highest court of German law, the Bundesverfassungsgericht (federal constitutional court) is located here. Another highlight is the oldest German 'informatics' faculty which is part of the university of Karlsruhe (the Fridericiana).
As a consequence, the city is full off lawyers and civil servants, but that doesn't bother people too much, because the thousands of students are a good counterbalance. In addition, Karlsruhe has some outstanding tourist 'musts':
The pyramid in the centre of the town, on the market place. It's the tomb of Margrave Karl Wilhelm of Baden-Durlach, who founded the city on 17 June, 1715, in the middle of the Hardtwald.
The palace of the Margrave with the tower, which is the centre of the fan, the original layout of the city. You can see the tower from anywhere in the city, if you stand on one of the major axis. The palace tower is located at 8° 24' 18'' eastern longitude and 49° 00' 54'' northern latitude, 117m above sea level.
The zoo and citypark, with its now famous enclosure for polar bears, is the most modern in Europe.
The Zentrum für Kunst und Medientechnologie ZKM (centre for art and media technology) has some 'interesting' exhibitions.
The Südstadt (southtown) is a city quarter with a very international population and many pubs and restaurants of all kinds.
You can get additional information from the Karlsruhe Official Website.