Tibet:

Standing at 117 metres (384 feet) in height and 360 metres (1,180 feet) in width, the Potala Palace is the most important example of Tibetan architecture. Formerly the residence of the Dalai Lama, it contains over one thousand rooms within thirteen stories, and houses portraits of the past Dalai Lamas and statues of the Buddha. It is divided between the outer White Palace, which serves as the administrative quarters, and the inner Red Quarters, which houses the assembly hall of the Lamas, chapels, 10,000 shrines, and a vast library of Buddhist scriptures. The Potala Palace is a World Heritage Site, as is Norbulingka, the former summer residence of the Dalai Lama.

Please answer a question about this article. If the question is unanswerable, say "unanswerable". What is Norbulingka?
former summer residence of the Dalai Lama