Journeys undertaken for religious reasons, usually to shrines or holy places. The concept predates Christianity and is common to several religions, reaching its highest development in Islam.* Although the practice of pilgrimage barely appeared in the earliest Christian centuries, the desire to visit the actual scenes of Christ's earthly life was a natural one. Among the earliest well-known pilgrims to the Holy Land were Constantine* and his mother Helena,* both of whom built churches there. From the veneration of the sites of the Savior's earthly ministry, the concept of pilgrimage was extended to the sites of the martyrdoms of His witnesses, which quickly acquired miraculous associations.