Although the Romans used their aqueducts to run cool water through the walls of rich people's homes, and Emperor Elagabalus even had a hill of snow built in his garden during summer to help keep cool, modern air conditioning has only been with us since 1902.
Willis Carrier is a fine example of American science and engineering - he only graduated from his engineering course at Cornell University in 1901, and the very next year he invented modern air conditioning.