Nalanda was a Buddhist university established in 450CE, and was the longest running university in Indian history. Among its many notable guests were the Buddha and Mahavira, and at its zenith accommodated over 10,000 students and over 2,000 faculty. However, it was sacked by Turkic Muslim invaders in 1193, and currently all that remains are extensive ruins that are spread over an area of 14 hectares. http://wikitravel.org/en/Nalanda