Paolozzi describes this sculpture, part cityscape, part elaborate machine, as an ''urban image''. The wheel, a recurring motif in his work, symbolises technology. Instead of using existing pieces of scrap metal, as he had in earlier sculptures, he started from scratch with this work. He designed a series of geometric units made from wax, then a team of assistants cast them in aluminium, before welding and painting them according to his instructions. This process, in which the artist is removed from the actual manufacturing, has been called ''industrial collage''.