This book addresses a little-studied area of the history of tourism, religious tourism, and pilgrimage and introduces a comprehensive economic analysis of their development from elite pursuits to a mass phenomenon. Focusing on Rome, Lourdes, and the Holy Land as destinations, the book showcases religious tourism as a key precursory factor in mass tourism in Italy and Europe. Departing from conventional historiographical timeframes, the authors demonstrate that the surge in tourism during the Italian “economic miracle” did not arise ex novo at that time but was part of a longer process of transformation originating prior to the Second World War. Diverse factors are discussed such as the social and economic role of the Catholic Church, its relationship to tourism, revolutions in transport technologies, rising wages, and increasing leisure time. Key questions are explored regarding religious travel (who, when, how) and how it gained momentum in the first half of the twentieth century. Drawing on a wealth of unpublished sources, many from the Vatican Archives, the book uncovers new religious, social, and cross-cultural perspectives and contexts for studying the economic history of tourism.