One of the world's most famous skyscrapers - the Empire State building in New York - is going green.
A project is underway to reduce the amount of energy used in the building by more than a third, saving millions of dollars a year.
One of the world's most famous skyscrapers - the Empire State building in New York - is going green.
A project is underway to reduce the amount of energy used in the building by more than a third, saving millions of dollars a year.