Portal:Australia/Anniversaries/October/October 20
![The Sydney Opera House.](http://upload.wikimedia.org/wikipedia/commons/thumb/4/40/Sydney_Opera_House_Sails.jpg/120px-Sydney_Opera_House_Sails.jpg)
- 1973 – The Sydney Opera House is opened by Queen Elizabeth II.
- 1987 – The Black Monday stockmarket crash causing the All Ordinaries Index to fall 25%, the single biggest one day drop in the market's history.
- 1989 – The Grafton bus crash occurs, with 21 people killed and 22 injured when a tourist bus collides with a semi-trailer on the Pacific Highway near Grafton.