The Stockholm City Line (Swedish: Citybanan) is a commuter railway tunnel beneath central Stockholm in Sweden which is used by the Stockholm Commuter Rail. The line is 7.4 kilometres (4.6 mi) long, double track and electrified. It has two stations: Stockholm City Station is located directly below T-Centralen, the central station of the Stockholm Metro. The Odenplan station is the other station, and is also served by the Green Line of the Metro. The line opened on 10 July 2017. Route.
https://en.wikipedia.org/wiki/Stockholm_City_Line