Wanda Hazel Gág's Millions of Cats (1928) is considered the oldest children's book still in print and has just entered the public domain. This timeless gem will delight cat-lovers with its beautiful pen and ink illustrations and hand lettering. The book won a Newbery award in 1929 and helped popularize the double-page spread in children's books.
Although Millions of Cats can be read as a sweet children's story about pets, it has also been interpreted as an anti-capitalist tale about "the barrenness of bourgeois living, greed, competition, environmental degradation, and senseless violence." This makes it an interesting read for all ages.
See also: Best older kid's literature from 1966