Opened on 3 July 1966, the brutalist structure is a grade II listed building for its architectural value and a prominent city centre landmark.

[1] The box is five storeys high on a rectangular plan except the ground floor, which is adjacent to the tracks.

The shape of the building is unique due to the congested nature of the site, hemmed in by railway tracks at below ground and local roads at street level.

The interior contains office facilities and communication equipment; the top floor is the signalling control room.

[2][10] The official list entry describes it as "very much a 'one off' constructed on a very difficult and congested site" and "a dramatic building of exceptional architectural quality with a strongly sculptural form".