What was the name of the second garden city built in 1920?

The second garden city built in 1920 was named Welwyn. This concept of garden cities was developed by Ebenezer Howard and aimed to combine the advantages of both urban and rural environments. Welwyn was designed to promote a healthier lifestyle with green spaces, ample gardens, and low-density housing, which differentiated it from typical industrial cities of the time.

Hampstead, Letchworth, and Brasilia, while significant in their own right, do not fit the criteria of being the second garden city built in that period. Letchworth was actually the first garden city, established in 1903, while Hampstead is not categorized as a garden city project. Brasilia, built much later in the 20th century, was a planned city in Brazil aimed at promoting development in the interior of the nation, rather than adhering to the garden city principles. Thus, Welwyn stands out as the correct answer in the context of garden city development in the early 20th century.