There are three things that you must not-and indeed cannot-miss.First, there is Sydney Harbor Bridge, one of the largest single-arch bridges in the world.Second, the Sydney Opera House is a famous landmark that most visitors greatly anticipate seeing.Finally,don't miss Fory Denison, where prisoners were kept in solitary confinement for days on a diet of bread and water. The best way to get around is by boat or hydrofoil, both of which have regular services leaving from Circular Quay. If you prefer to do things at your own pace, why not hire one of the many boats available for this purpose?