Armenian Cathedral of the Holy Cross

The Cathedral of the Holy Cross (Armenian: Սուրբ Խաչ եկեղեցի, romanized: Surp Khachʿ egeghetsʿi, Turkish: Aghtamar Kilisesi or Surp Haç Kilisesi) on Aghtamar Island, in Lake Van in eastern Turkey, is a medieval Armenian Apostolic cathedral, built in 921 as a palatine church for the kings of Vaspurakan and later serving as the seat of the Catholicosate of Aghtamar. After the Armenian genocide in 1915, it got abandoned and now turned into a museum.

Source: Wikipedia (CC BY-SA 4.0) — https://en.wikipedia.org/wiki/Cathedral_of_the_Holy_Cross,_Aghtamar