St. Mary Church is an ancient Assyrian church located in the city of Urmia, West Azerbaijan Province, Iran. It is considered by some historians to be the second oldest church in Christendom after the Church of the Nativity in Bethlehem in the West Bank.
Current old building of the church belongs to Sasanian era and its interior design is a combination of Sasanian and Arsacid architecture.
It is believed by some Assyrian and Christian historians that it had been a Fire temple at first in which Zoroastrian priests used to pray. At Jesus Christ' time of birth, three priests observed a shining star moving toward east. They considered it as a sign of awaited Messiah's birth and traveled to Jerusalem to meet him. After coming back they converted the fire temple to a church. 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 visit. Wikipedia