Koln in 2 days

Lots of suggestions here:
http://www.koelntourismus.de/en/cologne-cathedral-metropolis-on-the-rhine.html

My personal favourites are all located in the historical core of the city, just steps from the main train station:

• the Dom of course, including climbing the 508 steps up the bell tower which lead you past the world's largest bell

• Roemisch-Germanisches Museum, great for the Roman history of the city

• Museum Ludwig, one of my favourite collections of modern art

• Wallraf-Richartz-Museum, famous for its extensive collection of medevial paintings but also graphics and sculptures (for me, the impressionist sculptures were the highlight)

• Museum für Ostasiatische Kunst, the first German "Museum of East Asian Art"

• about a dozen Romanesque churches are in the centre - just pick a couple

• try out one of the many pubs and be sure to drink a "Koelsch", the local beer that's served in pretty small glasses

Dom (Cathedral, probably Germany's best known church)walking tour of Old TownKölsch beerMuseum LudwigWallraf-Richartz MuseumSchnütgen MuseumChocolate MuseumRömisch-Germanisches MuseumI didn't see Beatrix's fine list until after I posted mine; she and I are thinking alike plus her list includes good ones not on my list.

If you've got about half a day or so left take the S-Bahn down to Bonn and visit the old town, Beethoven-House, the gardens around the palace which are packed with students hanging around or studying (well, maybe not in early September yet). Also make sure you spend time in a beer hall in Cologne in the evening.

Agree with everything so far, old town center in Koln. If you are traveling by train, everything is very walkable. If in a car, park accross the river from the Cathedral near the train bridge and walk accross.

I was there in early September a few years ago and happened upon the Rathaus's open house, a rare chance to see some historic pieces they keep locked up in the attic as well as meet the uberBergermeister.

Nearby Bonn is a great town also. Bonnfest is in early September. If you get the chance, go. I went early in one trip (before visiting Octoberfest). In many ways it's better than Octoberfest, less touristy but very lively and no 10:30 curfew like at Octoberfest.

The regulation beer glass is a tall thin .2 liter glass or a .25 liter stemmed glass. The classic glass (pitcher?) people associate with Germany, called a Mas, really only exists in Bavaria but they used them at Bonnfest.

Thanks for all the great suggestions. Beatrix, thanks for the website link.