If your parents are anything like mine, they're probably always banging on about how their home city was so much nicer and cleaner in their day. Now there's an interactive bird's-eye view map that lets you explore Melbourne as it was 70 years ago - and compare it to the modern day.
Perhaps the most interesting revelation is how the city's boundaries have continually crept outward as the population grew. Fascinating stuff. You can play around with the map yourself here.