Conversation so far:
when was australia day first celebrated on 26 january
The state of Victoria adopted 26 January as Australia Day in 1931, and by 1935, all states of Australia were celebrating 26 January as Australia Day
how is australia day celebrated in sydney
On Australia Day, Sydney has boat races including a ferry race and the tall ships race
how is australia day celebrated in adelaide
On Australia Day, Adelaide celebrates with a parade, concert, fireworks, and a cricket match.

Question: what is the signicance of the holiday
Self-contained rewrite: what is the significance of australia day