Why have the aztec ruins in mexico city not been dug up?

The Aztec ruins in Mexico City had not been dug up due to the archeological sites being so close to modern-day infrastructure. Excavation would have to be done slowly as carefully due to modern sewers, pipes, and subway rails. Also, the Aztec capital was built on a lake bed and has to often be pumped out when the areas flood.  

ever since wwii tmthey always did hated each other.

you should think about the answers you give and expect the same form your questions.