The world-famous Sydney Harbour Bridge spans the harbour, connecting the northern and southern parts of the city. The 503m-long and 53,000tonne-metal arch bridge is one of the widest and heaviest in the world. It can be crossed by car, train, or better yet on foot, to get a full sense of its proportions. For a sweeping 360° view, climb the 200 steps up the southeast pylon to a height of 87m (small museum inside). Adventurous types can even climb up it!