In the first book, The Wonderful Wizard of Oz (1900), the walls are green, but the city itself is not. However, when they enter, everyone in the Emerald City is made to wear green-tinted eyeglasses; this is explained as an effort to protect their eyes from the “brightness and glory” of the city, but in effect makes everything appear green when it is, in fact, “no more green than any other city”. This is yet another “humbug” created by the Wizard. In this book, the Wizard also describes the city as having been built for him within a few years after he arrived. It was he who decreed that everyone in the Emerald City must wear green eyeglasses, since the first thing he noticed about Oz after he landed in his hot air balloon was how green and pleasant the country was.