The Koralm railway connects the Austrian cities of Graz and Klagenfurt. It is 126 km long and designed for a maximum speed of 250 km/h. Centerpiece is the 33 km long Koralmtunnel. It has two tunnels, which are covered by the Koralpe mountain range at a height of up to 1,200 meters. Construction started in 1999 and the line will open on 14. December 2025.