Altstadt
The Altstadt (Old Town) is the historic quarter of the city that runs along the river's south side for about a mile. Moving from west to east you'll find Alte Universität (Old University) and the Universitätsbibliothek (University Library) which contains manuscripts from the Middle Ages. Nearby Studentenkarzer (Student Jail) was used for recalcitrant undergraduates from the 16th century to the start of the 1900s. In the centre of Marktplatz (Market Square) is the late Gothic Heiliggeistkirche (Church of the Holy Ghost) which lies in the shadow of Schloss Heidelberg (Heidelberg Castle). This splendid Renaissance fortress contains the Deutsches Apotheken-Museum (German Pharmacy Museum).
North of the river
Cross the river via Alte Brücke (Old Bridge) and you'll find Philosophenweg (Philosopher's Way) which provides terrific views of Altstadt. A 20-minute walk north brings you to Thingstätte, a relic of Nazi Germany. This amphitheatre was specially created to rally people to the cause but now it's a haunting reminder of Germany's dark past.
Eating and drinking
In the heart of the Altstadt is Schnitzelbank which was once a cooperage but is now a wine bar. This little eatery serves authentic German cuisine, including Badische Schäufele and Wiener schnitzel, and good beer and fine wines, in an environment that appears to encourage complete strangers to talk to one another. Herrenmühle is located in a delightful old building and offers a small menu that delivers great quality. Close to the Alt Brücke, Wirtshaus zum Nepomuk has a menu of traditional regional dishes with a contemporary twist. This 18th-century town house provides a relaxed environment, whether eating in its dining room, parlour, courtyard or terrace.
Nightlife
Unsurprisingly for a city with a large student population, Heidelberg is a lively place, particularly in the evenings. The Untere Straße (or Pub Mile) has a good selection of pubs. Marktplatz has Max Bar, popular with academics, artists and artisans. You'll hear DJ-spun sounds at Nachtschicht, which is popular with the bright young things of the city. Tangente is a small club in the Altstadt that has a good line in house music. For something a little more traditional, Cave 54 is where you'll hear big classic jazz and big band swing, as well as programmes of live jazz performances.
Shopping
The mile-long, pedestrianised stretch from Bismarckplatz to Marktplatz is a delightful destination in its own right and offers famous brands and chic boutiques. For quirky indie shops, try the Altstadt and the Bergheim and Neuenheim areas. Heumarkt and Untere Straße have a good selection of speciality shops. And for high-end boutiques selling fabulous fashion, furniture and the like, try Sofienstraße, which is between Bismarckplatz and the main street.