The Spaso-Transfiguration Old Russian Monastery, classified as a first-class monastery, is located in the city of Staraya Russa. It was founded by Martiry, who in 1192, under the Novgorod prince Yaroslav Vladimirovich, built several cells and a wooden church here in honor of the Transfiguration of the Lord, consecrated on the day of the Assumption by the Archbishop of Novgorod. Grigory consecrated this church and named it a monastery, appointing its founder Martiry as the abbot. In 1193, Martiry was elected Archbishop of Novgorod and passed away on August 24, 1199; he was buried in Novgorod, in the narthex of the St. Sophia Cathedral. The monastery has repeatedly suffered devastation during Lithuanian and Swedish raids, but each time it was restored.

The Transfiguration Cathedral was built in 1442 and features a five-tiered iconostasis in the Byzantine style. The monastery houses parts of the holy relics of 50 saints, which were transferred from the Novgorod St. Sophia Cathedral in 1805, as well as the miraculous Old Russian icon of the Mother of God, celebrated on May 4. This icon measures 3 arshins 14 vershoks in length and 2 arshins 14 vershoks in width, adorned with a rich robe of jewels, and its value is approximately 12,000 rubles. The icon depicts the Mother of God with the Christ Child on her left arm, possessing a majestic appearance. According to tradition, the icon has been in Staraya Russa since the 10th century and was brought here by Greeks from Olviopol, Kherson province. In 1570, due to a plague outbreak, it was moved to the city of Tikhvin and remained in the Tikhvin Mother of God Monastery until 1888, when, at the request of citizens and with the permission of the Holy Synod, it was ceremoniously returned to Staraya Russa. In 1892, a new spacious church was consecrated in its honor. On the first Sunday after the Exaltation, a procession is held with the carrying of parts of the holy relics around the monastery. A spiritual school operates at the monastery. It is affiliated with the Krechevsky Nikolayevsky Monastery, located 3 versts from Staraya Russa, although the time of its founding is unknown.