What is the theme in Travels in Hyper Reality: Essays by Umberto Eco?

Authenticity is a major theme throughout this book, particularly in the first essay, "Travels in Hyperreality". Eco describes the creation and maintenance of "Fortresses of Solitude". The fortress was a place for Superman, whom Eco suggests is a good representation of an American, to go for solitude and to immerse himself in physical representations of his memories. The physical representations included robots that were so realistic they would easily be mistaken for being alive.