We arrived at the Fagus factory on a Saturday with the intention to participate in one of the guided tours which take place on Saturdays and Sundays. However, because there was an event scheduled on Sunday there was no tour on Saturday (since they were already setting up things for the event the next day).
Therefore, we had to take a tour with an audio/video guide. But we were lucky: the workers preparing the event didn't mind that we walked around in the factory so we got to see the same as during a guided tour (and maybe even more?).
Next to the audio guide tour, we also bought the 3-in-1 ticket (UNESCO visitor centre, Fagus-Gropius-exhibition and Gallery). The visitor centre does not add much to the info you get from the audio guide, but you can play with a media wall with information about all WHS (surprisingly addictive!).
The Fagus-Gropius-exhibition in the former warehouse provides five floors of background info about Fagus, shoes in general and even wood in general. While very well done and certainly interesting, we got the impression that there is too much space to fill - the upper floors become very high level. The Gallery is located in the former warehouse basements and is an art exhibition (can be skipped in our opinion).