Sioni Cathedral is situated in historic Sionis Kucha (Sioni Street) in downtown Tbilisi, with its eastern facade fronting the right embankment of the Mtkvari River. It was initially built in the 6th-8th centuries and was restored multiple times. Sioni Cathedral was the main Orthodox Cathedral and the seat of Catholics Patriarch of All Georgia until the Holy Trinty (Sameba) Cathedral was consecrated in 2004. However, it still holds the venerated Grapevine Cross (exhibited at the left of the altar) forged by St. Nino, a woman from Cappadocia who preached Christianity in Georgia in the early 4th century.
Sioni Cathedral was the place where the Russian Imperial manifesto on the annexation of Georgia was first published on April 12, 1802, when the Russian commander-in-chief in Georgia, General Karl von Knorring, assembled the Georgian nobles in the Cathedral surrounded by Russian troops. The nobles were forced to take an oath to the Russian Imperial crown and any who disagreed was taken into custody.