Drepung Monastery, located at the foot of Mount Gephel, is one of the "great three" Gelukpa university monasteries of Tibet. The other two are Ganden and Sera.
Drepung is the largest of all Tibetan monasteries and is located on the Gambo Utse mountain, five kilometers from the western suburb of Lhasa.
Freddie Spencer Chapman reported, after his 1936-37 trip to Tibet, that Drepung was at that time the largest monastery in the world, and housed 7,700 monks, "but sometimes as many as 10,000 monks."
Since the 1950s, Drepung Monastery, along with its peers Ganden and Sera, have lost much of their independence and spiritual credibility in the eyes of Tibetans since they operate under the close watch of the Chinese security services. All three were reestablished in exile in the 1950s in Karnataka state in south India. Drepung and Ganden are in Mundgod and Sera is in Bylakuppe.
Information based on http://en.wikipedia.org/wiki/Drepung