The Enthronement Anniversary of Karekin II, the Catholicos of All Armenians, is observed worldwide every October 27. This day commemorates the enthronement of Karekin II, who became the Catholicos in 1999, following the death of his predecessor, Karekin I. The Armenian Apostolic Church, one of the oldest Christian churches, celebrates this event, reflecting on its historical significance as Armenia was the first country to adopt Christianity as its state religion in the early 4th century. The Catholicos serves as the spiritual leader and chief bishop of the church, with the position historically filled by an election from the National Ecclesiastical Assembly, which includes clergy and community representatives. The Mother See of Holy Etchmiadzin in Vagharshapat is the seat of the Catholicos and the headquarters of the Armenian Apostolic Church, symbolizing the church's enduring heritage and role in Armenian identity.