An interesting concept of how the earth would look if all humans disappeared and the planet went back to its natural state, unimpeded by the modifications of man. It quickly went from very interesting to mildly interesting to boring and repetitive to not even worth finishing. It only took a couple of episodes to get it: internal systems fail, buildings start to break down, nature creeps back in, once mighty structures crumble, etcetera etcetera and so on until not a trace of man's existence remains. The first time it was a great watch but then every other episode was variations on a theme. We didn't even bother watching the last few episodes and skipped series 2 altogether.