These surviving freestanding buildings were purposely constructed for use by congregations (or used at an early date).The "church" (Greek ekklēsía, 'assembly') is traced to Pentecost and the beginning of the Christian mission in the first century and was not used in reference to a building.According to the Catholic Encyclopedia the Cenacle (the site of the Last Supper) in Jerusalem was the "first Christian church.[5][6][7][8][9][10] St. Thaddeus Monastery or Qara Kelisa[11] (meaning 'black church') in Chaldoran County, Iran is also noted by UNESCO World Heritage Centre as relating to 66 AD: "According to Armenian tradition such a location was chosen because saint Thaddeus built the earliest church—parts of which are still believed to be in place as the base of the old section—upon the ruins of the temple.[12][13][14] Church buildings of the 1st to 4th centuries (AD 30–400), either excavated archaeologically or substantially preserved.