Welwyn Garden City was founded by Sir Ebenezer Howard in the 1920s following his previous experiment in Letchworth Garden City. Howard had called for the creation of planned towns that were to combine the benefits of the city and the countryside and to avoid the disadvantages of both.
The Garden Cities and Town Planning Association had defined a garden city as
In 1919, Howard arranged for the purchase of land in Hertfordshire that had already been identified as a suitable site. On 29 April 1920 a company, Welwyn Garden City Limited, was formed to plan and build the garden city. The first house was occupied just before Christmas 1920.
The town is laid out along tree-lined boulevards with a neo-Georgian town centre. It has its own environmental protection legislation, the Scheme of Management for Welwyn Garden City. Every road has a wide grass verge. The spine of the town is "Parkway", a central mall or scenic parkway, almost a mile long. The view along Parkway to the south was once described as one of the world's finest urban vistas.
Since 1974 Welwyn Garden City has been part of the Welwyn Hatfield District or Borough. It had a population of 46,619 in the UK census of 2011.