Ratnagiri (Oriya: ରତ୍ନଗିରି) was once the site of a mahavihara, or major Buddhist monastery, in the Brahmani and Birupa river valley in Jajpur district of Odisha, India. It was part of the Puspagiri University, together with Lalitgiri and Udayagiri.
Excavated site Ratnagiri
Ratnagiri monastery in Jajpur district of Odisha crowning flat hill-top is affording a panoramic view of the surrounding might have been chosen for the seclusion for the serene and calm atmosphere necessary for monastic life and meditation studies.
Excavation conducted by Archaeological Survey of India during 1960's yielded the remains of an impressive Stupa (Stupa 1) surrounded by a large number of votive Stupas of varying dimensions, two quadrangular monasteries (Monasteries 1 and 2), a single-winged huge monastery with beautiful carved doorjamb and lintel, spacious open courtyard, cells and verandah facing the courtyard with spacious sanctum enshrining colossal Buddha. The existence of temple with curvilinear tower is only one of its kind discovered in Odisha.
From the impressive remains and large number of sculptures, discovered during excavation, it is clear that the Buddhist establishment of Ratnagiri, dating from circa 5th century CE witnessed a phenomenal growth in religion and architecture till the 13th century CE. Large number of stone sculptures, few bronze and brass image of Buddha and Buddhist pantheon recovered during excavations tend to prove that Ratnagiri was a great Tantric center of Buddhism comparable to that of Nalanda in Bihar.
A large number of clay sealing, found during excavations, bearing the legend Shri Ratnagiri Mahavihariya Arya Bhikshu Samghasya have helped in identifying the name of Ratnagiri monastery. By the end of the 13th century CE, it was on decline, decadence is discernible in architecture and sculptural art of Ratnagiri. Through no longer in an affluent condition the Buddhist establishment at Ratnagiri continued till about the 16th century CE.
Ratnagiri was established no later than the reign of the Gupta king Narasimha Baladitya in the first half of the sixth century CE, and flourished until the twelfth century CE. A Tibetan history, the Pag Sam Jon Zang, identifies Ratnagiri as an important center in the development of the Kalachakratantra in the 10th century CE, an assertion supported by the discovery of a number of votive stupas, plaques, and other artifacts featuring Kalachakra imagery.
A large-scale excavation was conducted at the site between 1958 and 1961. The report of these excavations was published by the A.S.I. Mitra (1981 and 1983) uncovering much of what is known today. The main stupa dates to the 9th century CE and was likely built on the site of an earlier, Gupta-era stupa. Seals were found bearing the legend Sri Ratnagiri Mahavihariya Aryabikshu Sanghasya, helped identify it. Prominent, well-preserved standing statues of the bodhisattvas Vajrapani and Padmapani can be found in niches in a portico. Monastery No. 2 features a central paved courtyard flanked by a pillared veranda around which are eighteen cells, a central shrine featuring an image of Shakyamuni in Varada Mudra flanked by Brahma and Sakra, and elaborately ornamented entrance porticos.
According to Amit Jha, a lecturer in the Department of History at Sri Aurobindo College, Delhi University, "Ratnagiri comprises two magnificent monasteries, also rebuilt more than once. One of them was double-storyed and had an extensive courtyard with two sides of it having a number of cells for habitation of monks. Besides, we have archaeological remains of six temples, thousands of small stupas, 1386 seals, myriad sculptural relics and architectural pieces of daily use. The largest stupa was 47 feet (14 m) square and 17 feet (5.2 m) high surrounded by four minor stupas. There are hundreds of miniature votive stupas decorated with lotus petals and beaded tassels."
- Mitra, Debala (1981 and 1983) Ratnagiri (1958–61), Vol. I (1981) & Vol. II (1983), published as SI. No. 80 of the A.S.I.'s "Memoirs of the Archaeological Survey of India" 
- " Magnificent samples of Buddhist architecture", Brindha, G. The Hindu, Friday, Aug 29,2003
- Iconography of the Buddhist Sculpture of Odisha, Donaldson, Thomas Eugene. Abhinav Publications: 2001. ISBN 81-7017-375-2
- Photos of Ratnagiri
- Video Documentary of Ratnagiri 
- Travelogue on Ratnagiri, Udaygiri & Lalitgiri
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