Heidelberg used to be the administrative center of the entire Kurpfalz region.
Tips for day trips Neckargemünd with the medieval fortress of Dilsberg; the old Roman town of Ladenburg; Schwetzingen, the German Versailles, with its castle park; the cathedral and imperial city of Speyer; Worms with the romantic imperial cathedral are just examples of many destinations worth seeing.
You can find much more information at www.kurpfalz-tourist.de