Situated on the Mtkvari river, it was an important city in ancient and early medieval Iberia as Georgia was known to the Greeks and Romans. Archaeological studies have demonstrated that the place was inhabited in the 3rd millennium BC. The settlement grew larger and, in the 4th century BC became a city with thriving commerce and culture. Ruins of a fortress, rich baths, pagan sanctuaries and even a Jewish temple suggest the importance of the city. Burned structures and round catapult stones indicate the city may have been under a siege and subsequently sacked in c. 3rd century BC. The new era in Urbnisi’s life began with the conversion of Iberia to Christianity. It now became a major center of Georgian Orthodox culture. From the 6th to 7th centuries, a strong system of fortifications was erected around the city that did not prevent, however, the Arab commander Marwan (caliph from 744 to 750) from capturing the city in the 730s. Following the invasion, it declined to a small village. However, the Urbnisi monastery of St Stephen continued to function as a center of a Georgian Orthodox diocese.
The monastery is a 6th-7th-century three-nave basilica which was rebuilt twice in the 10th and 17th centuries. Quite a simple and large church, it is based on twelve strong pillars for three naves. There are many inscriptions on the walls of the monastery which are thought to be the examples of the 6th-7th-century Georgian alphabet.
Both Urbnisi Monastery and the Ruisi Cathedral are known for a major ecclesiastic council convened here in 1103-1104 by the Georgian king David the Builder to cope with problems within the church hierarchy.