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 Östersund in Sweden, and two southbound connections to Oslo, the Røros Line and Dovre Line. The Coastal Express ships (Hurtigruten: Covering the Bergen–Kirkenes stretch of the coast) call at Trondheim, as do many cruise ships during the summer season. Since 1994 there is also a fast commuter boat service to Kristiansund, the closest coastal city to the southwest. Every morning the Hurtigruten ships have one southbound and one northbound arrivals and departures in Trondheim. A car ferry route from the port of Flakk in the northwest of the municipality, connects Trondheim with Fosen. Various bridge projects over the Trondheim Fjord