Final answer:
The first developed garden city typically refers to Letchworth Garden City in England, designed by Unwin and Parker, following the City Beautiful movement's influence. This foundational urban planning concept has been carried into modern times with projects like Gardens by the Bay in Singapore.
Step-by-step explanation:
The first developed garden city alludes to a concept that emerged from the early urban planning movements, particularly the City Beautiful movement. Pioneered by visionaries such as Olmsted and Burnham at the Columbian Exposition in 1893, the movement advocated for urban reforms, including more substantial park areas, boulevards lined with greenery, and the addition of suburbs. This approach significantly influenced later urban planners including Raymond Unwin and Barry Parker, who are renowned for their designs incorporating these principles. Although the question mentioned Unwin and Parker, it may be in reference to their work in Letchworth Garden City in England, which was the world's first garden city designed by Unwin and Parker and founded by Ebenezer Howard. It's worth noting that the concept has evolved in contemporary times as exemplified by projects like Gardens by the Bay in Singapore, which embodies the idea of a 'city in a garden' with its widespread use of flora to enhance quality of life.