Karlsruhe was founded in the 18th Century, planned by margrave Karl-Wilhelm. Therefore it has the typical fan-shaped structure of an absolutistic city with a palace in the middle.
Behind the palace there is a wonderful park, which blends into a forest further away (which is perfect for jogging!). In summer, the park bursts with students playing frisbee, volleyball or just hanging around.
As there are eight academies in Karlsruhe, the population is quite young. So there are -compared to the size- lots of bars, cafés and clubs for every taste. There are also many cultural offerings like musea and theatres and lots of cultural and sporting events.
The townscape is very idyllic - especially compared to cities like Koblenz. This comes first from the traffic, which is being directed on ring-roads. Besides, most of the city center is a pedestrian area, so that you get mad if you want to go there by car. The other thing is that it was the residence of some grand dukes, who covered the city with squares, statues and diverse buildings.
Transportation is not a problem in Karlsruhe. The train connections to other cities are very good and you even get directly to Strasbourg and Paris (it takes only three hours, they say in their ads). Also the local public transport is very good with a lot of tram lines and even more buses, which cover the whole region. So you don't have to bother how to get around there.