You've really captured some of the most beautiful corners of one of my favorite cities – brings back great memories! I actually lived in Heidelberg for three years as a student.
Just a small historical note: Heidelberg was indeed a capital – but of the Electoral Palatinate (Kurpfalz), not the Palatinate (Pfalz) as we understand it geographically today, which is now part of Rhineland-Palatinate. The Electoral Palatinate was a distinct territory within the Holy Roman Empire, stretching across parts of what are now Baden-Württemberg and Rhineland-Palatinate.