Manglisi Sioni is located near Daba Manglisi, in Tetritskaro municipality. According to historical sources, the first stone cathedral was built here during the proclamation of Christianity as a state religion in the 30s of the IV century. According to Leonti Mroveli, bishop John brought sacred relics and abundant treasures to build churches in Georgia. He delayed at Manglisi before arriving in Mtskheta and started to build the temple, where he left part of the Holy Cross of Christ.