Saint Mary Church is among the oldest churches of Iran and the world and it is located on Khayyam Street in Urmia. Narratively, this is the first church in the Orient the construction of which dates back to 32 A.D. The current building of Saint Mary Church, especially its domes, arches and pillars are a mixture of the architecture of Sasanid and Parts Era. The entrance door is a short door that is opened to the courtyard. It has no benches or place for the priests' preaching or confession. On the right and left of the entrance hall of the church, there are two vestibules with inscribed gravestones that are the burial point of Christian missionaries. The current gravestones in vestibules belong to three leaders of East Church of Assyria and one of the Orthodox Church Russian missionaries. On the right hand of altar, there is a narrow and short corridor on the right wall of which there is a wall stove, which has been used to bake the holy bread. Next to this wall stove, there is a stone pond on the wall used to baptize children. This church has been reconstructed several times and it has given uneven shapes. There are no special adornments, plasterwork or painting in this church since Assyrians have a special belief that no adornments or ornaments are used in their churches.