The Berlin North-South main line, also called the North-South link (Nord-Süd-Verbindung) is an electrified railway line in Berlin which was opened in 2006. It is an important component of the “mushroom concept” (Pilzkonzept) adopted for long-distance and regional rail services through the city. Its core is an approximately 3.5 km (2.2 mi) long Tiergarten tunnel under the Tiergarten in Berlin. The tunnel section includes the underground level of Berlin Hauptbahnhof and the Potsdamer Platz regional station. The above-ground section of the line includes the Berlin Südkreuz station.

Berlin Hauptbahnhof is the main railway station in Berlin, Germany. It came into full operation two days after a ceremonial opening on 26 May 2006. It is located on the site of the historic Lehrter Bahnhof, and on the Berlin S-Bahn suburban railway. The station is owned by DB InfraGO, a subsidiary of Deutsche Bahn AG, and is classified as a Category 1 station, one of 21 in Germany and four in Berlin, the others being Berlin Gesundbrunnen, Berlin Südkreuz and Berlin Ostbahnhof.