Trondheim is a critical battleground for both factions. Trondheim was the name of a planet in the Hundred Worlds of the Ender's Game book series. Trondheim has an international airport, Trondheim Airport, Værnes, situated in Stjørdal, which is Norway's fourth largest airport in terms of passenger traffic. Værnes has non-stop connections to cities such as London, Amsterdam, Copenhagen, Stockholm and Berlin, among others. The domestic route Trondheim - Oslo is among the busiest air routes in Europe with around 2 million passengers annually. Busiest air routes Major railway connections are the northbound Nordland Line, the eastbound Meråker Line to Åre and
Trondheim to replace the ferry have been planned, but none have begun construction. Trondheim also boasts the northernmost (since closure of Arkhangelsk tram in 2004) tramway line in the world: the Gråkallen Line, the last remaining segment of the Trondheim Tramway, is an route (which is mostly single-track outside the innermost parts of the city; except the stretch between Breidablikk and Nordre Hoem stations) which runs from the city centre, through the Byåsen district, and up to Lian, in the large recreation area Bymarka. Trondheim boasts the world's only bicycle lift, "Trampe". The bus network, operated by AtB, runs throughout most