Udayagiri (ଉଦୟଗିରି) is the largest Buddhist complex in the Indian state of Odisha. It is composed of major stupas and monasteries (viharas). Together with the nearby complexes of Lalitgiri and Ratnagiri, it is part of Puspagiri University. The heritage sites are also known collectively as the "Diamond Triangle" of the "Ratnagiri-Udayagiri-Lalitgiri" complex. Per epigraphical artifacts found at the site, its historical name was “Madhavapura Mahavihara.” This Buddhist complex, preceded by the Ratnagiri and Lalitgiri sites, with their monasteries, is believed to have been active between the 7th and the 12th centuries.