I went for a walk yesterday (see the red track below). I’ll provide a signed photo to the first person who can state where I am and why I am visiting this city. Good luck!
Hint: My starting and ending coordinates (green and red markers) were N 51° 53.059’, W 8° 31.922’ so it should be easy to determine where I am. As for why I am here … well, that’ll be more difficult. It might help to know that I delivered a lecture yesterday afternoon (July 3) and am participating in a public panel this evening.