In Behind the Beautiful Forevers, is there a chapter or section in the story that describes a wall separating two different worlds?

Katherine Boo describes a wall that separates the poor people who live in Annawadi slum from the wealthy people who drive past the slum on their way to and from the international airport. This is also the wall that gives the book its name. 

Boo describes the wall as follows: 

"The airport people had erected tall, gleaming aluminum fences on the side of the slum that most drivers passed before turning into the international terminal. Drivers approaching the terminal from the other direction would only see a concrete wall covered with sunshine-yellow advertisements. The ads were for Italianate floor tiles, and the corporate slogan ran the wall's length: "BEAUTIFUL FOREVER BEAUTIFUL FOREVER BEAUTIFUL FOREVER." (pg. 36-7)

The purpose of this wall is to hide the poverty of the slum from the rich people who come to Mumbai for business, diplomacy, or tourism, and it is successful in doing that: Boo writes that, with the wall built, "only the smoke plumes of Annawadi's cooking fires could now be seen." The rest of Annawadi is hidden.

The purpose of Boo's book is to make the struggles of the people living in Annawadi visible. That is why the book is called, Behind the Beautiful Forevers.