Sydney, the capital state of New South Wales and the most populous city in Australia and Oceania. Located on Australia's east coast, the metropolis surrounds the world's largest natural harbor and sprawls about 70 km (43.5 mi) on its periphery towards the Blue Mountains to the west, Hawkesbury to the north and Macarthur to the south. In addition to hosting events such as the 2000 Olympics, Sydney is amongst the top fifteen most-visited cities in the world, with millions of tourists coming each year to see the city's landmarks. Its natural features include Sydney Harbor, the Royal National Park, and the Royal Botanic Garden. Man-made attractions such as Sydney Tower, the Sydney Harbor Bridge, and the Sydney Opera House, are also well known to international visitors. Kingsford-Smith Airport is the main airport serving the metropolitan area, one of the world's oldest continually operating airports. The Central station is the main hub of the city's rail network.