Cologne and Dusseldorf trip in the works

My wife and I will be going back to Germany later this year to stay with some friends in Frankfurt.  I am planning on heading up for some Kolsch and Altbier in Cologne and Dusseldorf, and I’m taking suggestions from anybody who has a “must visit” place to get some of the local beverages.  Any input would be greatly appreciated. Thanks.
PW

In Cologne: Haus Töller for dinner, Hausbrauerei Päffgen and Braustelle for beer.

You can walk to Uerige, Im Fuschen, Zum Schuessel breweries and the Schneider tap house in the Altstadt in Duesseldorf. Have one at each (.25 liter), then go back to your favorite for more.

Great suggestion - I took a walking beer tour in the Alstadt that did this and it was a lot of fun.

There is also a new Alt brewery there, Kuerzer, so I might have to go back someday.

I visited that one on my tour.  IIRC it has fermenters that are on the second level and only the very bottom of the cone sticks down through the concrete ceiling.  That was the first time I’d seen anything like that.

It is common in big breweries, usually 800 bbl fermenters, which are outside, but the bottoms are in the cellar.

Everything you need to know about 'Dorf:
http://draftmag.com/features/alt-reality-dusseldorf-altbier/

Papa joes in Cologne -

If you take the ICE, Brussels is only like 3 hours from Frankfurt. The beer is way better there.