The Church of the Nativity in Bethlehem is one of the few medieval monuments whose decoration, preserved, even if partially, in its original state until recently, can be almost completely reconstructed on behalf of surviving mosaics and wall paintings, in situ inscriptions, and rich written evidence from the Middle Ages and early modern times. The decorative program, dating back to the third quarter of the twelfth century, represents a unique testimony of its time, in its historical, theological, and art-historical aspects. The crusader lining of one of the most important monuments of early Christianity takes up local, Byzantine, and European traditions, eastern and western impulses to emphasize a locus sanctus that supports the Christian claim to universality. It is close to a miracle that such a diverse network of sometimes contradictory requirements and traditions as the one extant in crusader Holy Land merged into an exceptionally consistent programme.