I should warn you that if you aren't careful you might end up catching the wrong train back to…read moreCologne. The reason I say that is because there is a light rail platform that runs between Cologne and Bonn, and unless you are planning on getting off somewhere in between, you might find out that the trip takes a lot longer than you originally anticipated. Anyway, the main line platforms are above as opposed to below, and the trains are a lot bigger as well. Oh, you can also interchange to the U-bahn, especially if you are planning on heading out to Konigswinter.