Hannover: The Deutsche Bahn has a station at the hannover
exhibition grounds, simply called Messebahnhof. During CeBIT or
Hannover fair, trains with up to 12 cars can go there, from
older cars over IC cars up to the ICE. The overhead wire is
directly (isolated, of course) connected to the building.

Photo by Sven Herzfeld (s.herzfeld@maschsee.han.de)