Sydney's Olympic Park is a great place to go for a trip on the weekend. You can swim at the Aquatic Centre, or ride a bike around and explore this huge site, or, like these kids, take advantage of this really nifty fountain to cool off.
Panorama (also showing time-shift if you follow the child in blue!):
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The main Olympic arena (background) and the 'Superdome' (where they staged basketball and other sports) behind the fountain.
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A great fountain to ride your bike through to help cool off:
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The pyramid is a grass covered mound built of toxic soils from this site, which was contaminated from decades of industrial pollutants:
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I stood under the jets for a while: