Somewhere in tractate Sukkot of the Babylonian Talmud the rabbis talk about building sukkot up in trees and on camels. These days, there are a lot of high-end, high-concept sukkot out there. It's all the rage, since the 2010 Sukkah City in Union Square. But I like this picture from Williamsburg. These more simple sukkot are stuck up and down the sides of a wall.