It was unique in containing below it a tunnel for a tramway, which started just north of Southampton Row, passed beneath Aldwych and continued to the Thames Embankment: this Kingsway tramway subway joined the North and South London tram systems. In 1958 the disused tunnel was reopened at the southern end to make a new connection, the Strand Underpass, for light traffic between Waterloo Bridge and Kingsway on order to reduce congestion. Also beneath Kingsway was a branch of the Piccadilly tube line from Holborn to Aldwych. It is now closed with no service but the platform at Holborn used for the branch is used for TV and film sets that require underground scenes. During WW2 the branch was used to store art treasures from the British Museum, including the Elgin Marbles.