Why did the twelfth-century canons at the Lateran church (San Giovanni in Laterano) in Rome claim the presence of the Ark of the Covenant inside their high altar? This book argues that the claim responded to new challenges in the aftermath of the First Crusade in 1099. The Christian possession of Jerusalem questioned the legitimation of the papal cathedral in Rome as the summit of sacerdotal representation; so what may be described as translatio...