Stefano Fenoaltea devoted more than five decades of great scientific activity (1967-2020) to more than five decades of Italy’s economic history, 1861-1913, a central period to understand Italy’s economic development, its industrialization: a huge research project of which his last book, Reconstructing the Past. Revised Estimates of Italy’s Product, 1861-1913 represents an important and vital part. The article focuses on this complex book, which is Fenoaltea’s last grand effort to understand post-Unification Italy and to propose a general method to study economic history. It is an important book. It offers new empirical material and new accurate thoughts to an old historiographical controversy: Gaetano Salvemini, and all historians who have pointed to a failure of Liberal Italy, would regard the latest Fenoaltea’s reconstructions as grist for their mill. His methodology, however, is broad and far-reaching, not limited to the historical context from which it originated