World's Oldest Christian Churches

There are some of the oldest churches of the world in Urmia in the northwest of Iran, as you read here: http://en.wikipedia.org/wiki/Christians_in_Iran -> Yet many old churches remain in Iran from the early days of Christianity. The Church of St. Mary in northwestern Iran for example, is considered by some historians to be the second oldest church after the Church of Bethlehem in Palestine. A Chinese princess, who contributed to its reconstruction in 642 AD, has her name engraved on a stone on the church wall. The famous Italian traveller Marco Polo, also described the church in his itinerary during his visit.