Drepung Monastery is located on the Gambo Utse Mountain, 5 kilometers from the western suburb of Lhasa. As the largest and richest monastery ever in Tibet, it was founded in 1416 by a disciple of Tsong Khapa under the patronage of a noble family and later enlarged by the Fifth Dalai Lama. The second, third and forth Dalai Lama once stayed here. The monastery covers a floor space of more than 200 thousand square meters. At its peak, it had a registration of more than 10,000 thousand monks. Many high and learned lamas had learned here. The main structures of the monastery include the Main Assembly Hall (known as Tshomchen), four Tantric colleges and Ganden Palace (Ganden Potrang). The tshomchen of Drepung, covering 4,500 square meters and supported by 183 pillars in the center of the monastery, is the best-known, most powerful tschomen of all the monasteries in Tibet. It can seat 8,000 monks. In addition, a great deal of ancient books and sutras are preserved in the monastery.