The Old Heidelberg University, Germany's oldest university, was build in the early 1700s. It now holds the Rector's Office, the Old Assembly Hall, and the University Museum. The museum shows the history of the university beginning with its foundation in 1386 through today. Exhibits, portraits, and documents explain this history in three different sections. There's one about the Palatinate electors, one about the Baden era, and one about the twentieth century. In addition to the permanent exhibits, every few months there is a new special exhibit opens.

In the square in front of the building is a fountain of a lion, called Löwenbrunnen. The lion was the symbol of the Palatinate. At the back of the Old University, visitors can see the student prison, which was in use until 1914 and is now one of the most popular attractions in the city. Students could be put in the prison from two days to four weeks depending on the offense, although life there was quite comfortable.