The oldest-surviving blueprint from medieval times details the layout and construction of a village and monastery called the Plan of St. Gall. Now archaeologists and craftspeople are building that community, first described in 800 A.D., using only the tools and methods available back then. Author Kristen Ghodsee has visited the site and writes about it in her new book, “Everyday Utopia.” She tells The World’s Marco Werman that the medieval vision of a utopian community has much to teach the modern world.