"Is it true that there's a water tower in Centrepoint to keep it stable?" John, Kirribilli

It's true and it follows the same rule of thumb as a fish bowl in the hands of a four-year-old. Says maintenance supervisor Dan Whellens: "When a force, like a squall or a child, shakes an object like a tower or a fish bowl one way, the water acts as a counterbalance stabilising the 4,067 tonne structure, protecting all the helpless inhabitants."

Designer Donald Crowne seemingly threw caution to the wind in his plans when he constructed a focal point to revitalise the heart of the city, and actually embraced the gusty blows. By installing a 167,000 litre water tower in the gold turret atop the structure, he made the 309-metre Sydney Tower one of the safest buildings in the world. Opened in 1981, the Tower took six years and $36 million to erect.

According to tests conducted at Sydney University's aeronautical wind tunnel, it can withstand 172km/h winds. And the water tower isn't just a sophisticated science project. It supplies the extinguishing power of the tower's $1 million fire protection system. Centrepoint has hosted about 17 million visitors to date.

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