You don’t need a De Lorean to go back in time when you’ve got a freilichtmuseum. These are open-air-museums where you can experience first-hand how locals lived in the past.
There are two near to Cologne, the Freilichtmuseum Kommern in the Eifel, which is huge and needs a full day to do it justice. Or the Bergisches Freilichtmuseum Lindlar, which is a half hour drive from the city and much smaller, but no less beautiful.
The Landschaft Verband Rhienland who run the Freilicht museum, have bought, relocated and lovingly restored old buildings that were either going to be demolished, or have been donated to the museum due to their historical value. Here you can spend the day enjoying the beautiful countryside, nosing around old cottages and houses, and learning about how the buildings were made and how people used to live in them in the past.
Fresh bread is baked daily in an old fashioned bakery and you can see ribbons being made on a 19th century loom that still works today; there are pigs, chickens, horses and cows; a bar and a shop and a number of houses all rescued, relocated and refurnished to look just as they did in the past. At €12 for a family of four (kids are free) the price is right for a half day excursion at least.
Check it out for yourself: http://www.freilichtmuseum-lindlar.lvr.de/de/startseite.html