The Cathedral of the Theotokos in Vilnius is the episcopal see of the Eastern Orthodox Christian Metropolitan of Vilnius and all Lithuania.
In 1415 – 1795 it was a cathedral temple metropolitan bishops of Kiev of the Ruthenian Orthodox Church and the Ruthenian Uniate Church within the Polish–Lithuanian Commonwealth.
Wikipedia https://en.wikipedia.org/wiki/Cathedral_of_the_Theotokos,_Vilnius
Coordinates 54°40'51.979" N 25°17'32.442" E
