Steven marlin, not all seven wonders are supposed to be man made.  There are also nominees for natural seven wonders.  Currently seven natural wonder of the world is,

• Grand Canyon
• Great Barrier Reef
• Harbour of Rio de Janeiro
• Mount Everest
• Aurora
• Parícutin volcano
• Victoria Falls

But these wonders listed by CNN is done without consensus. And it is believed to be high time there should be voting as well.