Visit the website, it's technik-museum.de
The site is in English too and it shows a history about how they landed the 742 in Karlsruhe/Baden-Baden, took it apart, transported it over the rhine river to Speyer, and how they did rebuild it there.
There also is a similar story about the Concorde F-BVFB which went to their Sinsheim-exhibition.
They offer some other quite interesting planes, Antonov22, Dassault Mirage, Tupolew144...always worth a visit...
BTW, the 742 is open, You can enter the cabin, walk around, they removed many walls, You really see some detailled technical stuff. The cockpit can be sseen, they even put a platform on the left wing...
Search the database for LH
747-200 D-ABYM, eventually in the preserved/museum or what it's called category.