Which garden city was first developed and started in 1902?

The garden city that was first developed and started in 1902 is Letchworth. Letchworth Garden City is significant as it was the landmark project conceived by Ebenezer Howard, who envisioned a new kind of urban development that integrated green spaces with residential and commercial areas. Howard's principles aimed to create self-sufficient communities surrounded by "green belts," promoting a balance between nature and urban living.

Letchworth served as a prototype for the garden city movement, influencing urban planning in various parts of the world. Its development was characterized by its carefully designed layout, which included parks and well-planned residential areas, reflecting Howard's vision for healthy urban living. This model inspired other garden cities, such as Welwyn, which was developed later after Letchworth.

The other options, while significant in their own contexts, do not represent the first garden city established under Howard's principles. Welwyn, for example, was developed after Letchworth, Hampstead is not recognized as a garden city in the same sense and is more associated with suburban development, and Brasilia, designed in the 1950s, reflects a radically different approach to urban planning.