Sydney Tower is the tallest structure in Sydney and the second one in Australia. It is also known as Centrepoint Tower, AMP Tower and other. Construction of Sydney Tower Centrepoint shopping centre began in late 1970 with the first shops opening in 1972. The office component was finished in 1974 and the final stage of the complex, the Sydney Tower, was opened to the public in 1981. The 56 cables weight seven tonnes each. The windows comprise three layers. The turret's nine levels include a cafe, two restaurants, the Observation Level, and Sky Tour, the largest simulated virtual ride in the southern hemisphere. Sydney Tower features three attraction which are Observation Deck, OzTrek Ride and Skywalk, which is additional to the general admission charge. Skywalk is a breathtaking outdoor tour on the roof top of the highest tourist attraction. About a million visitors a year appreciate the wonderful views, often stretchin for over 80 kilometres.