During a Trade Fair season I had to be in Cologne where all hotels were fully booked or extremely overpriced. Hotel Silencium is a small hotel in a wooded residential district that embued a sense of peace and tranquility no matter what time of day or night. Truly lovely grounds, very comfortable rooms (I had a mini suite with balcony) and enormously helpful and efficient staff. I highly recommend it. It is however, rather far from the city center (22E taxi fare or a short walk takes you to the local UBahn train station and you can reach the city center sights of Cologne within 20 minutes.