Typical Cologne beer is called "Kölsch" and served in bars around town in small glasses of 0.2l (so that the beer can be drunk while it is still very cool), so-called "Stangen" - but waiters will be fast to bring you a new one, once your old one is finished. In some bars, the waiter (called "Köbes" in local language) will put a new glass in front of you without being asked when he sees an empty glass, so it is easy to lose track of how much you drank. Each beer will be a pencil line on your coaster. To stop the beer from coming, put the coaster on top of your empty glass. If you buy it bottled, take either "Reissdorf", "Früh" or "Mühlen", which are rated highest by Cologne citizens. There are so many bars and pubs to choose from that you could spend most of the night looking going from one bar to the next. A really great bar is the Irish Pub, Flanagan's, in Altstadt located down below a building. Almost everybody speaks English in there if that's what you are looking for, and they have a really great Karaoke night on Sundays. The clientele is very friendly.

For traditional breweries, head to the Altstadt around the Dom, where the "Früh Kölsch" brewery is the most authentic place, famous both with visitors and locals. You will find a younger crowd at "Hellers Brauhaus" on Roonstraße, near metro station Zülpicher Platz. Furthermore the "Päffgen", on the all-bar street Friesenstraße close to the Friesenplatz, and the "Mühlen" near Heumarkt are traditional brewery pubs but less touristy than the "Früh". Most Altstadt pubs are somewhat scorned as "tourist traps" by locals, however; prices here are usually higher than e.g. on Zülpicher Straße.
There are a lot of modern bars and lounges all around town. More mainstream ones are on Zülpicher Straße. For something more independent and funky on this street, try Umbruch (funky) or Stiefel (punky). The Low Budget on Aachener Straße next to Moltkestraße metro is a nice, unassuming, punky bar which features a fine selection of drinks and often hosts concerts, poetry or cabaret sessions.
A lot of stylish places are in the so-called Belgian quarter between Aachener Straße and the Ring, e.g. famous M20 or the Hallmackenreuther.

Cologne stands on ground that is steeped in history. Numerous cultural monuments from the past 2000 years, such as the famous Roman Dionysus mosaic, the Jewish Mikwe, the medieval Overstolzenhaus and the Gürzenich hall, or modern structures such as the opera house (1957) and the Media park (from 1989 onwards) are to be found at the foot of the cathedral.

The characteristic elements in the history of the City of Cologne: commerce, transformation and transport, religion and veneration of the saints and modern art are combined within a highly confined area in the city centre, embodied by Cologne central railway station (1890 - 1894) and its restored glass and steel structure, the cathedral itself and the adjacent museums (Ludwig Museum, Römisch-Germanisches Museum).