The Urbnisi cathedral of Saint Stephen the Protomartyr (Georgian: ურბნისის წმიდა სტეფანე პირველმოწამის სახელობის საკათედრო ტაძარი, romanized: urbnisis ts'mida st'epane p'irvelmots'amis sakhelobis sak'atedro t'adzari), commonly known as the Sioni church of Urbnisi (ურბნისის სიონი, urbnisis sioni), is a Georgian Orthodox cathedral at the village of Urbnisi in Georgia's east-central Shida Kartli region. The church is a relatively large three-nave basilica, originally built in the 6th century and reconstructed in the 10th and 17th centuries. The church walls bear several inscriptions, some being among the oldest executed in the Georgian alphabet. The cathedral is inscribed on the list of Georgia's Immovable Cultural Monuments of National Significance.