Kölsch is the local beer and much tastier than Altbier which is brewed in Duesseldorf, Cologne's biggest rival.
Go to a 'Brauhaus' of which there are plenty in the old town. Be aware, waiters tend to be very rude.
Frueh (close to the main station/cathedral)
Muehlen / Gaffel (near Heumarkt)
Paeffgen (near Friesenplatz)
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