Sydney Tower is Sydney's tallest free-standing structure, and the second tallest in Australia (with the Q1 building on the Gold Coast being the tallest). It is also the second tallest observation tower in the Southern Hemisphere (after Auckland's Sky Tower, though Sydney Tower Eye's main observation deck is almost 50 m (164 ft) higher than that of Auckland's Sky Tower). The name Sydney Tower has become common in daily usage, however the tower is also known as the Sydney Tower Eye.