Kathmandu,[a] officially the Kathmandu Metropolitan City,[b] is the seat of federal government and the most populous city in Nepal. As of the 2021 Nepal census,[4] there were 845,767 inhabitants living in 105,649 households and approximately 4 million people in its surrounding agglomeration. It is located in the Kathmandu Valley, a large valley surrounded by hills in the high plateaus in central Nepal, at an altitude of 1,400 metres (4,600 feet). The city is one of the oldest continuously inhabited places in the world, founded in the 2nd century AD. The valley was historically called the Nepal Mandala (the name for the cosmic elements of water Dha mandala in Newari, and cosmos), and has been the home of the Newar people, a cosmopolitan urban civilization in the Himalayan foothills. The city was the royal capital of the Kingdom of Nepal and hosts palaces, mansions and gardens built by the Nepali aristocracy. It has been home to the headquarters of the South Asian Association for Regional Cooperation SAARC) since 1985. Today, it is the seat of government of the Federal Democratic Republic of Nepal, established in 2008, and is part of Bagmati Province.