The show has a silly premise; people suddenly disappear, without any explanation, then the things that are left behind decay and crumble. Eventually, there is little evidence we were ever here. There are only a few possible explanations for why we suddenly vanish; we're all beamed up at the same time by aliens or some supernatural event like the rapture takes place. Both possibilities are equally absurd. If aliens wanted our planet they would just engineer a doomsday weapon that kills all humans. If its the rapture, then all the sinners are supposed to be left behind to fight the last war (according to the Bible).
Aside from lacking a credible premise the show has some interesting depictions of what happens to things when they are left to the elements. Buildings crumble and animals go feral. That is no suprise but the depictions are pretty cool. It shows things like skyscrapers weathering away and falling down.