In 1970 a concrete replica of the St John's Cross arrived in Iona sitting incongruously on the deck of a puffer delivering the island's annual supply of coal. What is the story behind this intriguing replica? How does it relate to the world's first ringed 'Celtic cross', an artistic and technical masterpiece, which has been at the heart of the Iona experience since the eighth century? What does it tell us about the authenticity and value of replicas? In this fascinating book, Foster and Jones draw on extensive interdisciplinary research to reveal the composite biography of the St John's Cross, its concrete replica, and its many other scale copies. They show that replicas can acquire rich forms of authenticity and value, informed by social relations, craft practices, creativity, place and materiality. Thus, the book challenges traditional precepts that seek authenticity in qualities intrinsic to original historic objects. Replicas are shown to be important objects in their own right, with their own creative, human histories - biographies that people can connect with. The story of the St John's Cross celebrates how replicas can 'work' for us if we let them, particularly if clues are available about their makers' passion, creativity and craft.