Cathedral of the Theotokos, Vilnius
Vilnius, Lithuania · built 1346
The Cathedral of the Theotokos in Vilnius is the episcopal see of the Russian Orthodox Diocese of Lithuania. Between 1415 and 1795, it was the mother church of the Ruthenian Orthodox Church and the Ruthenian Uniate Church (following the 1596 Union of Brest) within the Grand Duchy of Lithuania and then the Polish–Lithuanian Commonwealth.
Church data from Wikidata (CC0). Summary from Wikipedia (CC BY-SA).