Tongatapu is the main island of the Kingdom of Tonga and the location of its capital Nukuʻalofa. It is located in Tonga's southern island group, to which it gives its name, and is the country's most populous island, with approximately 71,260 residents (2006), 70.5% of the national population, on 260 square kilometres. Its maximum height is 65 metres. Tongatapu is Tonga's centre of government and the seat of its monarchy.