With the opening of Serdika II on 31 August 2012 the station became an interchange between the Red and Blue lines.

However it is not a true interchange (such as platforms 3, 4, 5 and 6 of Canning Town station in London), but an interconnected station, in a similar manner to the Washington Metro’s Farragut West and Farragut North stations.

[3] These are located about six meters (20 feet) below ground and, along with the opening of Serdika II station, a large section of the old city has been exposed and is in full view both around and inside the two stations.

[4] Serdica is one of only three metro stations in the world where the same line passes through the station twice in a pretzel configuration, the others being the Monument Metro station on the Tyne and Wear Metro in Newcastle upon Tyne, England, and Voorweg RandstadRail station on the Randstadrail of The Hague, Netherlands.

Media related to Serdika Metro Station at Wikimedia Commons