The building by the Rhine river houses the chocolate museum: you can learn about the cocoa plant , see tropical trees in the greenhouse, look how the machines make and package chocolates, taste them...
Just some 10-15 minutes walking from the cathedral, along the nice river promenade.
Fondest memory: The liquid chocolate fountain - biscuit included ;-)
and the tropical trees greenhouse
Fondest memory: The Imhoff-Stollwerck chocolate museum! on the Rhine. Oh yeah baby... Its the Chocolate Museum that Britney Spears visited this year & declared than chocolate was just like a You-Know-What! It's a little building on the Rhine, just down from the main bridge (Hohenzollernbruecke)on Rheinauhafen. 10DM in. Free choccie samples. History of choccie (so what, get to the good bits!), a beeeeeeeeeyoouuuuuuuuuuutiful smell wafting around the building. Of course you got the cafe selling choccies and coffee and you can sit by the window watching the Rhenish waves lapping at the window. Popular with school groups (!) Well worth an hour of your time.
Fondest memory: Ludwig museum is just behind the cathedral close to the train station and the Ludwig museum. This is the oldest museum in Cologne.