Hello,
I'll be in Cologne for about 2 weeks on a business trip in late January and I'll have 1 free weekend to explore the city.
Please give some suggestions on day trips, sights, etc.
Are there any castles that are close enough for a day trip?
Thanks in advance.

ttt

Take the Rhine steamer up to Königswinter. It's like a Teutonic theme park.

Restaurant: Zur Malzmuehle, Heumarkt 6. A little tough to find as it's on the part of Heumarkt on the*other* side of the Deutzer Bridge tram line. It's "Typisch Koelsch" (typical Cologne)--but Bill Clinton found it and ate there. I discovered it as an exchange student in the 1970's and it was jsut as good in April of 2005 when we went back. Must sees: the Catherdral, and in particular, three items, the reliquary of the Three Magi in the Choir, the altar by Stephan Lochner (right of the center crossing) and the Gero Cruxifix from the 900's (to the left of the center crossing). Climb the right tower for an amazing view. Second, visit the Roman-German Museum adjacent to the Cathedral. It was built around a mosaic found during WW II while digging a bomb shelter. Cologne was founded by the Romans in 50 AD--part of the roman North Gate is still extant on the Cathedral Plaza with another arch in the museum itself. For Modern Art lovers, there is the Wallraf-Richartz museum, also by the Cathedral.Note that most museums are closed on Mondays. Also people watching at an open-air cafe on Neumarkt is fun.

Wonderful bierstube by the cathedral where they serve a local brew called "koelsch" (kelsh). It's called Fruh (froo) and you will have a marvelous experience.

Thanks for the all the suggestions.
Question about safety at night.
I saw a picture of the DOM at night and it looked awesome. How safe is it to walk around at night in that area? I'll be staying at the Maritim hotel.
Thanks.

Well, safety... there are a lot of homeless people that seem to be around the Dom however it is very near the main train station and so there are always some people around at every hour.

Can't think of any nearby castles unless you travel down the Rhein. The city is fun to explore however in January; may be a bit brisk.