I have been able to make a couple of short visits to Köln since I have a friend from near the area. The old city sits on the Rhine river but it is the gigantic cathedral (dom) in the middle that stands out most. (2003, 2007)
An overview of the city and the Rhine River beside it
Bright buildings in the old market (Alter Markt) along the riverside as well as a bit of history in the statues nearby as you can see the bullet holes from the war
The old rathaus (town hall) of the city.
View of the city from the cathedral tower and our group visiting the cathedral (dom) and bell
The famous glockenspiel of the House of 4711 where eau de cologne was created