Sorry, Mina -- I haven't had much luck with this one. The Greek is, umm, Greek to me. Using Google translate only says:
100 χρόνια ΑΧΙΛΛΟΠΟΥΛΕΙΑ = 100 years of ACHILLOPOULIA
which isn't much help.
Your piece is clearly a 100 year commemorative coin of something, but I don't know what.
It was produced in 2001, so it is a modern coin, token or medal. As a modern coin, token or medal, it is worth its weight in gold, but only if it is, in fact, gold.
Have it tested and evaluated at a jeweler. The jeweler can easily test for gold content,