Echmiadzin Cathedral

Etchmiadzin Cathedral is the mother church of the Armenian Apostolic Church, located in the city dually known as Etchmiadzin and Vagharshapat, Armenia. It is usually considered the first cathedral built in ancient Armenia, and often regarded the oldest cathedral in the world.

The original church was built in the early fourth century—between 301 and 303 according to tradition—by Armenia's patron saint Gregory the Illuminator, following the adoption of Christianity as a state religion by King Tiridates III. It was built over a pagan temple, symbolizing the conversion from paganism to Christianity. The core of the current building was built in 483/4 by Vahan Mamikonian after the cathedral was severely damaged in a Persian invasion. From its foundation until the second half of the fifth century, Etchmiadzin was the seat of the Catholicos, the supreme head of the Armenian Church.

Source: Wikipedia