Cologne was a decent time
I spent three days in Cologne. The first night I spent it on a strip of bars and restaurants that was filled with "college" kids. It reminded me of my college years for sure lol. On two separate days I walked to the cathedral and it truly is breathtaking. I actually attended a church service on the Sunday that I was there. Im not religious but it gave me goosebumps (the good kind). Kolsch beer is very interesting and you will find no shortage of it around the city.
Insider Tip:I took a "cologne free walk" and discovered hidden gems all around the city. This is a must. If I ever go back to Cologne it will be during "Carnival" because with three days I feel that I pretty much saw everything there is to see.