I agree with Language as it is the foundation of all of our knowledge.

The Wheel-magnified our mobility many fold

Controlling Fire-cooking meats made food easier to digest, allowing for more higher brain functions to develop

The Pulley, the Lever, the Fulcrum,-are the essential basis of all of our machines.

Roads-rapidly increased economic growth.

electric lighting-increased our ability to operate safely at night

The assembly line-rapid production of goods, lowering costs of owning them

Powered Flight-shrank the world for us.

TV-its often a swamp-but it is a very powerful communication tool

Microchips-the basis of all our computing devices

The Internet-this one is pretty obvious

3D printing will revolutionize production in years to come.

As you guys can tell, I have played a lot of the "Civilization" series.