"Saint Sunday" is an Orthodox church in Sofia, dedicated to the worldly Sunday martyr Sunday. Next to the church there is a square with the same name.

St. Sunday Church is the cathedral of the Sofia Metropolis. It occupies the place of the old Koruscheshme Square, which is famous for its spring, overshadowed by centuries-old trees. Today the square is called "Saint Sunday".

In the nineteenth and twentieth centuries, the temple was also called the "Holy King," as the relics of Serbian King Stefan Uros II (1282-1321) were preserved in it. Around 1460 during a plague epidemic, Sofia Metropolitan Silvanai transferred them from the village of Trepche, north of Pristina, to today's Lyulin Monastery, St. Cyril and Methodius (also called St. King).

Subsequently, they were transferred consecutively to the St. George rotunda, to the temple "Stlessless Powers" (or "St. Archangels"), to the Metropolitan Church of St. Marina.