The 309m-tall Sydney Tower (still known as Centrepoint by many Sydneysiders) offers unbeatable 360-degree views from the observation level 250m up. The visit starts with the 4D Experience, a short film giving you a bird's-eye view of city, surf, harbour and what lies beneath the water, accompanied by mist sprays and bubbles. Then it's up the lift to the viewing area. The guided Skywalk (adult/child $80/50) takes you outside to circumnavigate the tower along a ledge.
Tickets are cheaper online, or as part of a Sydney Attractions Pass. The entrance is on the 5th floor of the Westfield shopping centre, near the food court but surprisingly poorly signposted.
There are two revolving restaurants: an extremely mediocre buffet and a better fine-dining establishment, though you'd be better off heading to the revolving restaurant in the Australia Square building.