Sioni Virgin Mary’s Assumption Cathedral is a central- domed building. It is built of Algeti Stone. The façade is plain and of yellow sandy colour. There are many shrines in the church of the temple: the Grace Stone of David Garejeli, the skull of Apostle Thomas, St. Nino’s Cross etc. The Georgian kings inherited the Cross from the ancestors and it rested in Svetitskhoveli Cathedral. With this Cross Mirian King of Georgia blessed his son Bakar as King before his death.
Obviously, Sioni Cathedral must have been built along with the building process of Tbilisi, as the historian Juanşar of XI century says: “Guaram Kurapalat renewed the foundations of Tiflis Sioni” (VI c.). The Cathedral was completed in times of Duke Adarnase in VII century. According to the legend, Guaram and Adarnase are buried in it.
The Cathedral was destroyed and robbed by the enemy many times, so its first appearance is not known to us. In 1226 when Jalal-ed-Din of Khwarezm Shah invaded Tbilisi, he ordered to dismantle Sioni Dome and to place his throne there. The icons of the Lord and Virgin Mary from Sioni Cathedral were rested on Metekhi Bridge. The population of Tbilisi was ordered to insult the icons. More than one hundred thousand Georgians refused to insult the icons and on that day they were tortured to their deaths in the name of Jesus Christ. During the first invasion of Timur Lang in 1386 Tbilisi was severely damaged. Sioni Cathedral was also robbed. The conqueror took away the unique library from Tbilisi. Presumably the process of construction, which was commenced by King Alexander I Didi (“the Great”) in the 15th century, must have included Sioni Cathedral too. A three-circle bell tower was also built there in 1425. Starting from XVI century, the Sioni Cathedral was robbed and damaged several times during the Iranians invasions. During the invasion of Agha Mohammad Khan, Sioni Cathedral was burnt and the wall painting was destroyed as well as the iconostasis and the three-circle bell tower, built by Alexander I.
After the abolition of the Kingdom of Kartl-Kakheti, in the 19th century, Sioni Cathedral was repaired several times. Georgian governor Pavle Tsitsianov began its restoration works during of which the Georgian trace was gradually lost and the Russian architecture style was brought in. Between1851-1855 Grigol Gagarin rebuilt the Sioni iconostasis and painted the cathedral. Unfortunately, the characteristic features of Georgian architecture and painting were lost. After the enthronement of Catholicos-Patriarch of All Georgia Ilia II, the Sioni Church restoration works were carried out intensively. The iconostasis was made According to the old Georgian specimens.