The Gialia Monastery is a ruined medieval Georgian Orthodox monastery dedicated to the Virgin Mary. Located in a forest some five kilometers from the coast near the small town of Polis Chrysochous, the ruins were identified, in 1981, by the Georgian scholar Wachtang Djobadze of California State University on the basis of the medieval Georgian accounts. It was not, however, until 2006 that a systematic archaeological research followed after the Georgian and Cypriot governments agreed to jointly investigate the ruins.
It was reported in 2008 that excavation evidence indicated the monastery was commissioned in the late 10th century by Georgian King David III Kuropalates and that renovations were made during the reign of David IV Aghmashenebeli (1089-1125). The monastery is certainly attested in the 12th century, when it was renovated at the behest of Queen Tamar of Georgia (1184-1213). Ancient Georgian sources report that it was in Georgian ownership until the 14th century, and graves and other items uncovered indicate that it was in use between the 14th and 16th centuries. It was reportedly plundered and destroyed in the 16th century, but appears to have been in use as recently as 1935, until final destruction by an earthquake in 1953.
Two main structures have been identified: the earlier Virgin church, and the later St. George's church dated probably to the 11th and 12th centuries respectively. Remains of Georgian paintings and inscriptions from the 13th and 14th century have also survived.
Visby Cathedral (also known as St. Mary’s Church) is the only survived medieval church in Visby. It was originally built for German merchants and inaugurated in 1225. Around the year 1350 the church was enlarged and converted into a basilica. The two-storey magazine was also added then above the nave as a warehouse for merchants.
Following the Reformation, the church was transformed into a parish church for the town of Visby. All other churches were abandoned. Shortly after the Reformation, in 1572, Gotland was made into its own Diocese, and the church designated its cathedral.
There is not much left of the original interior. The font is made of local red marble in the 13th century. The pulpit was made in Lübeck in 1684. There are 400 graves under the church floor.