The city of Bethlehem has been controlled throughout history by Romans, Byzantines, Crusaders, Mamluks, Turks, British, Jordanians, Israelis and the Palestinians. Constructed like a citadel over the cave where it is believed that Jesus was born, the Basilica of the Nativity was commissioned by Emperor Constantine and built in the 4th century. Shared today by Greek Orthodox, Armenians and Roman Catholics, it is the world's oldest working church and hosts pilgrims who come from all over the world to pray and meditate. Christmas celebrations are always moving and spectacular.