Its called a wonder because of the odd shape an they didnt have machines to help build the pyramids it extremly hard to do and people wonder how it was done.
I believe that the Pyramid of Giza is called a wonder because it is a truly impressive work of architecture especially since it was built in a time before modern construction tools like cranes meaning, that people had to manually carry, push or pull the stone blocks used to build the pyramids, up to wherever they were needed. This would be a very difficult task even with a ramp which, evidence suggests that they did have some form of ramp system.
