Heidelberg is the place that German Romantics made famous and Mark Twain made funny. The Neckar comes out of its wooded valley here and slips past a steep old town, a stone bridge with a gate, and above everything the red sandstone ruins of the castle. Visitors have been climbing up to look at it since the early nineteenth century, when poets and painters arrived and decided it was the most beautiful ruin in Germany. The damage was done by French troops in the 1680s and 1690s, in a war of succession, and a lightning strike finished the job later, so it was never a romantic wreck by design.
The university, founded in 1386, is the oldest in Germany, and students are still part of the street life. You can see the old student prison, where unruly undergraduates were locked up as a punishment and scribbled on the walls, and in the castle cellar is the Great Tun, an enormous wine barrel. The Philosophers' Walk on the north bank gives the classic view across the river, and is worth the short climb at the end of the day.
For motorcyclists, Heidelberg is the start of the Castle Road, which runs from Mannheim to Nuremberg through the Neckar valley and the hills of the Odenwald and Franconia. Leaving town along the Neckar to the east, you pass castles on hilltops, half-timbered villages and stretches of bendy road, with the river on one side and forested slopes on the other. Weekends are busy, and speed cameras are common, so ride sensibly. Traffic inside the city is heavy, and parking is awkward, so it is better to leave the bike at a garage and walk.
The population is around 145,000, so every service is available, with fuel stations on the main approach roads and every sort of food in the old town, from student cafes to restaurants with white tablecloths. Spring, when the blossom is out, and autumn, with the colours in the Odenwald, are the best seasons.