I was inspired by an article about how well the earth would do without us. Within 500 years all buildings would be half fallen or fallen, perfect homes for animals and plants. The forrest would soon grow in cities. After hand buildings aswell as pollutions would be taken care of by bacterias and micro-organisms. An ufo that came here in a couple of of hundred thousand years would not see many signs of that a gang of primates ones thought that they where the lords of the planet.