If you're in Sydney's CBD and can hear helicopters overhead, that's because Barack Obama is in town. According to 7 News, the former president of the United States touched down at Sydney Airport around 1pm and has since made his way — as part of a motorcade — up Oxford Street and into the CBD.
At the moment, it doesn't look like there will be any road closures or changes to traffic. Unfortunately the talk is not open to the public, but if you head to the AGNSW, you might be able to get an IRL sighting of the former president. Although you may not be able to get very close — security will be understandably tight.