Train from Koln to Berlin

4-4½ hrs is about right.

As for when, you might want to consider the price. German Rail offers advance purchase Dauer-Spezial fares for as low as €29 pP one way. However, these fares sell out well in advance, particularly for popular times. The lowest fare I could find with a quick check was €39, and that was an evening trip. During the day was €59 on some trains, more on others.

Thanks Lee

Has anyone taken the night train to Berlin from Koln arriving at I think it was 4:10am? How crowded was it and what do you do once arriving in Berlin so early?

Berlin Hauptbahnhof has its own website (also in English). I found two restaurants that open at 5:30 am except on the weekend and on holidays (6 am). You could always get a hotel room for the previous day and tell them you're not arriving until the early morning hours the next day, if they're staffed at night (many smaller places aren't.) Or get a taxi and ask the cabbie if he knows an all-night place where you can get breakfast - or better yet, leave early and get in at a decent hour, which I would perceive as safer, too.

You also might want to check out airberlin.com and germanwings.com for flights from Cologne to Berlin from €19 one-way incl. taxes. Flight time would be about an hour. Also Berlin is a city that never really sleeps. Many restaurants, bars are open 24 hours. Also, depending on when you're traveling you could take the circle line S-Bahn from Berlin's Hauptbahnhof (central station) and take it for one entire round around the city center. That's a cheap 90 minutes scratching the surface sightseeing tour that can be done at any time of day or night...