The Ingolstadt Rathaus. Wikimedia Commons photo.
The home of Adam Weishaupt and the Bavarian Illuminati doesn't have a lot of attractions themed to its secret society heritage, according to this BBC travel report. There is a small plaque outside of Weishaupt's former home, and you can take an Illuminati walking tour, although for those who aren't fluent in German, the beer tour might better bridge the language barrier. Google's English translation of the walking tour page says, "Forget Dan Brown, the number 23, and other myths surrounding the organization. On a serious historical foundation we want to shed light on the historical background - understandable and popular-scientifically processed."