Answer:
ROMAN EMPIRE
Contributions to today's society:
Government
Since no country today uses a true democracy, the Romans started what is considered to be the best form of government.
Religion
It was the Romans who crucified Jesus, creating the most influential religion in the world.
Architecture
Many bridges and roads in Europe, the middle east, and Africa were built during Roman times. The Romans uses arches and invented concrete.
Art/Literature
The Romans kept Greek literature and logic alive, which still is taught in schools around the world.
Warfare/Military
Military organization that is still used today was invented by the Romans.
Sports
Language
Numbers