Letchworth, founded in 1903 in Hertfordshire, was the first built realisation of Ebenezer Howard's garden-city idea, developed through a private company after the success of his 1898 book. Architects Barry Parker and Raymond Unwin laid out the town with low-density housing, generous gardens, tree-lined roads and a planned town centre, all girdled by a permanent agricultural greenbelt. The scheme aimed to combine the economic and social benefits of the town with the health and amenity of the countryside, capturing rising land values for the community. It was followed by Welwyn Garden City in 1920.
It turned Howard's garden-city diagram into buildable reality and became a global model for suburban and new-town planning. Its principles of greenbelts, neighbourhood layout and low-density living shaped 20th-century planning across Britain and beyond.