Australia day is celebrated annually on January 26th, as that marks the anniversary of the 1788 arrival of the First Fleet of British Ships at New South Wales as well as the raising of the flag of Great Britain at that location. In present-day Australia, however, celebrations focus much less on the arrival of the aforementioned ships, and instead concentrate more on the diverse society and landscape of the nation. Source: https://www.daysoftheyear.com/days/australia-day/