The Altstadt historical city center and Hauptstrasse main street. The Hauptstrasse leads from Bismarckplatz across the old town. Approximately one mile in length, it is reputedly the longest pedestrian shopping street in Germany.
The Castle: an audio guide tour of the castle and its grounds is available for a fee near the entrance. It is available in several languages, including English. There is also a statue to the German poet Johann Wolfgang von Goethe in the castle gardens. Currently covered with unsightly scaffolding [Sept 2012] but this is very normal.
The Philosophenweg which can be found on the northern side of the city. It provides a wonderful view across the oldest part of the city. Here you can find the site of the famous Merian Stich engraving which is a popular illustration of Heidelberg.
The Heiligenberg mountain which boasts a wonderful view over the old town.
The Thingstätte on top of Heiligenberg an open-air theatre built by the Nazi regime in 1934 to host propaganda events
Also on the Heiligenberg the remnants of a wall ancient Celts built to keep Germanic tribes out, the Heidenloch, a deep well with unknown origins, and the ruins of a 10th century cloister.
The Kurpfälzisches Museum on the Hauptstrasse contains interesting exhibits of items from Heidelberg's pre-history to modern times.
The old university on Universitätsplatz in the old city and the adjacent old armory which is now a student cafeteria but also open to the public.
Jesuitenkirche
has 1712 Baroque construction with modern touches inside.The Heiliggeistkirche church is only one of many large and small churches, but definitely the one with the most interesting history. During the dark ages, it was the shelter of the Bibliotheka Palatina, Germany's oldest library. The Bibliotheka was stolen and brought to Rome but eventually returned in pieces. Today, parts of it can be visited in the University Library also the oldest and probably the most valuable of its kind in Germany, which is situated close to the old university. View of cathedral from Heidelberg Castle
You can get a great view of the Heiliggeistkirche, Old Town, and the Neckar river bridge from the castle Schloss Heidelberg.
