This chapter explores the circumstances leading to the announcement of the first part of London’s Ringways plan, with the unveiling of the London Motorway Box in 1965. The chapter provides a description of the Ringway plans, including the later segments in Ringways 2 and 3. It assesses prior proposals for improving London’s roads, notably the Abercrombie plan and its five proposed rings, but identifies how the 1965 proposals were a major departure from this precedent, notably by making no effort to help traffic in central London. These changes reflected the powerful effects of data generated as part of the pioneering London Traffic Survey. London’s planned urban motorway network emerged as an accidental by-product of this traffic modelling exercise, rather than as an example of set-piece planning. The creation of the Greater London Council in 1965, replacing historic institutions that had been criticised for a lack of effective transport policy-making, thrust the Ringways proposals to the front of the council’s agenda with relatively little critical consideration.