The route continues through a bored tunnel under the Damrak, The Dam, Rokin, Vijzelstraat, Vijzelgracht, Ferdinand Bolstraat and the Scheldestraat.

The line continues underground past the RAI until coming above ground in the central reservation of the South Ring Road (A10) just before the southerner terminus.

The energy supply, security and other infrastructure of the North South line are controlled from the Sein-Energie en Telecomgebouw (Signal, Energy and Telecom building), also known as the SET building, located in the central reservation of the South Ring Road, west of the RAI metro station.

The concept of a North-South line running from Amsterdam-Noord through the Centraal Station to Schiphol was explored in the 1968 Stadsspor plan.

According to the plan the line would continue from Amsterdam Zuid through Amstelveen, along the Beneluxbaan and finally arriving at the airport.

When the North South line was eventfully constructed, the initial plan was for it to continue to the airport, but due to budget concerns this was abandoned.

[12][13] In the Noord-Holland provincial coalition agreement in 2019, GroenLinks, VVD, D66 and PvdA seemed to be in favour of extending the line north to Zaandam and Purmerend.