In a question regarding the Kosel there is a link to an Aish article. In the article it mentions in the name of a book "Legends of the Land of Israel" that the Kosel HaMaaravi was built by the poor.
The building of the Western Wall fell to the poor, and they worked hard to construct it, as they could not afford to hire laborers to do their work for them. When the enemy destroyed the Temple, the angels descended from on high and – spreading their wings over the Wall – said: "This Wall, the work of the poor, shall never be destroyed." (from "Legends of the Land of Israel")
Who authored this book? I have been unable to find such a title.