When author Phyllis La Farge and photographer Magdalena Caris recently took a journey from the city of Xalapa in the state of Veracruz to the town of Coatepec, they noted that on the facades of countless public and private buildings, improvised murals had been painted. The wit and exuberance of these wall paintings, whether commercial or simply decorative, suggested an urban visual lingo that could be traced to the ancestral murals of pre-Columbian Mexico, and La Farge and Caris decided that they deserved closer study. Somewhere between a scholarly investigation and a travel book, "Painted Walls of Mexico" documents these often anonymous interventions. As Homero Aridjis writes in the preface, ""Painted Walls" is not only an invaluable testimony to this undervalued art which is disappearing from our streets, but honors the unknown artists who, with humor and imagination but without the slightest recognition, convert the streets of their town into an open gallery."