Due to the nature of Singapore being a sovereign city-state, Singapore is its own capital -- the entire country is both a city and a nation. This makes Singapore very unique as a country, although it is not the only one of its kind. The two other city-states in the same situation as Singapore include Monaco and the Vatican City. Although Singapore does not have a capital city in the traditional way most countries do, the main island, Palau Ujong, or Singapore Island, acts as a capital in many ways. All of Singapore's governmental buildings of legislature are located on this island, which is responsible for a significant proportion of the population and land of Singapore. Singapore Island's population is nearly 5.5 million, while the nation's total population barely tops 5.6 million. Interestingly, Singapore's Pulau Ujong is the 20th most populous island in the world. It has an area of 710 square kilometers (274 square miles), rather small but comparatively titanic when compared to the 62 surrounding Singaporean islands that do not quite meet 10 square kilometers (4 square miles) in total.