Though it is a beautiful structure, the Sydney Harbour Bridge requires constant maintenance. When they put the first three coats of paint on it, it took 272 000 litres to do it. The bridge has to be repainted all the time - its a constant job. As soon as they have finished they start again. That's why Paul Hogan had a job there - painting the bridge!
They have even developed a special paint for the job. It dries out within a few seconds so that any paint drops are dry by the time they get to the cars far below.