What are really considered the Seven Wonders of the World?

There is a lot of debate and even different classifications have come up to define what are the actual Seven Wonders of the World. There are some that are considered the Seven Ancient Wonders and there are some that are considered the New Seven Wonders, but there seems to be a definitive list of the Seven Wonders which is the following: 
The Great Wall of China
The Taj Mahal
The Colosseum
Chichen Itza
Machu Picchu
Christ the Redeemer
Petra