Mid April, I will be doing a quick trip to CGN (arriving Sat am-leaving the next day back to EWR). As I've been to Koln a couple of times, I thought I'd do a side trip to city within a 20-40 min train ride. I'm not looking for museums, but merely want to do some walking around, sightseeing, shopping, eating etc for 3-4 hours mid day, as I will be staying in CGN. Most guidebooks (Fodors, Frommers etc) have only a page or 2 on each city, so was hoping an FT'er would be able to give me some help. If there is another city I should be considering, please let me know