Answer:
Religion.
Explanation:
The Greek civilization was 2500 years ago but it still influences western civilization. They developed democracy, the system of govern that is used all around the world nowadays.
Some of their stories and plays are still performed and read these days. Philosophers like Aristotle and Plato are still read these days because of their ideas. World mathematics is derived from the Greek language.
The only concept that is still not significant about the Ancient Greeks is their religion, they were polytheists while the main religion in western civilization is a monotheist.
I hope this answer helps you.
