Australia is an island continent located in Oceania with Canberra as its capital city. Some of its major cities include Sydney, Melbourne, Brisbane, Perth, and Adelaide. Australia is home to the Great Barrier Reef, the largest coral reef system in the world located along its northeast coast, and Uluru, a massive sandstone rock formation in the country's Red Centre. The British established the first European settlement in Australia in 1770 as a penal colony. In 1901, six British colonies formed the Commonwealth of Australia.