Cathedral of the Theotokos, Vilnius

The Cathedral of the Theotokos in Vilnius (Lithuanian: Vilniaus Dievo Motinos Ėmimo į Dangų katedra) is the main Orthodox Christian church of the Republic of Lithuania.

The cathedral was built during the reign of the Grand Duke of Lithuania Algirdas for his second Orthodox wife Uliana of Tver in 1346. It was constructed by Kievan architects with the blessing of Saint Alexius, Metropolitan of Kiev and all Rus', in 1348.

The Cathedral of the Theotokos is one of the most ancient churches of Vilnius, built before the christianization of Lithuania when the Grand Duchy of Lithuania was the last pagan state in Europe. It became an important spiritual centre for the growing Christian population of the Duchy. In 1495 the marriage between Grand Duke Aleksandras of Lithuania and Helena of Moscow, daughter of Ivan III, was held in the cathedral in the presence of Saint Macarius. It was there that Helena was buried in 1513.

After the conversion of Lithuania to Roman Catholicism, the Orthodox cathedral was protected by princes Konstanty Ostrogski and Konstanty Wasyl Ostrogski, who restored it after the collapse of the dome in 1506. After their deaths, the cathedral was taken over by the Uniate Catholic church in 1609 and was rebuilt in a style typical of the region.